During recrystallization, you followed three steps: (1) added ethanol to the reaction mixture to create precipitate, (2) dissolved the precipitate by heating, and (3) allowed the solution to sit unperturbed for at least two days. Why did you go through these three steps?
Answers
Recrystallization is a process used to purify solids. The three steps in the process are explained below:
1) Added ethanol to the reaction mixture to create a precipitate:
This is the initial step where ethanol is added to the mixture to dissolve the product that contains impurities. The addition of the solvent to the reaction mixture leads to the solubilization of the solid containing impurities.
2) Dissolved the precipitate by heating: Heating the solution evaporates the solvent and increases the solubility of the solid in the solution, leading to the formation of crystals. Solvent and solute must be able to dissolve each other in order to achieve this.
3) Allowed the solution to sit unperturbed for at least two days: During recrystallization, this step is very important since it allows the solution to cool down slowly, resulting in the formation of large crystals. The solution is kept sitting unperturbed until the crystals have fully formed and can be separated from the solution through filtration, giving a purified compound with high purity.
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Related Questions
why does it take more energy to evaporate water than to melt ice?
Answers
Answer:
The energy required to completely separate the molecules, moving from liquid to gas, is much greater that if you were just to reduce their separation, solid to liquid. Hence the reason why the latent heat of vaporization is greater that the latent heat of fusion.
Answer:
It takes longer to boil water than to melt ice because of the difference in the amount of heat required to overcome the forces of attraction by keeping the temperature constant during this time. ... This is the reason it takes longer in boiling than in melting.
C. How do the drops of polar liquids differ from those of nonpolar liquids?
Answers
Explanation:
Polar molecules or liquid are formed whenever the electronegativity separations of the bound atoms changes. Because once sharing of electrons equally between atoms in a diatomic molecule or even when polar bonds in a complex mixture cancel one another out, nonpolar compounds or liquid form.
If solid iron is dropped in liquid iron, it will most likely?
float.
sink.
freeze.
condense.
Answers
it will sink
Explanation:
the solid iron will sink because it is dense than the liquid iron I will sink and it will melt
Answer:sink
Explanation:
What causes air masses to move?
A: A difference in air pressure and temperature occurs.
B: Weather conditions change rapidly to produce storms.
C: A collision takes place bahween two natural wind patterns.
D: Long, narrow bands of wind blow in the upper atmosphere.
Answers
Answer:
the answer is A the temperature effects the movement of air by if its warm air it moves up and colder moves down while the pressure effects how fast and the directions it moves
Use the reaction below for the combustion of ammonia gas to
produce nitrogen monoxide and water vapor.
4NH3(g) + 302(g) → 4NO(g) + 6H₂O(g)
What volume of O2 is needed to react fully with 720. mL of
NH3?
a) 960 mL O2
b) 1.02 L O2
c) 720. mL O2
d) 540. mL O2
Answers
What is it called when elements combine to form a chemical compound?
Answers
Explanation:
A compound is a unique substance that forms when two or more elements combine chemically.Compounds form as a result of chemical reactions. The elements in compounds are held together by chemical bonds. A chemical bond is a force of attraction between atoms or ions that share or transfer valence electrons.hope it helpful ✌️✌️
the elements of group 15, 16, 17 are less reactive as they go down in the group of modern perodic tale. why ?
Answers
Answer: This is because the atomic radius increases with increasing electronic energy. This reduces the attraction for the valence electrons of other atoms, reducing reactivity.
A graduated cylinder contains 17.5 mL of water. A metal cube is placed in the cylinder and the water level rose to 20.3 mL. The metal cube has a mass of 30 g. What is the density of the metal cube
Answers
Answer:
10.71 g/mL
Explanation:
Initial Volume = 17.5 mL
Final Volume = 20.3 mL
Volume of cube = Final Volume - Initial Volume = 20.3 mL - 17.5 mL = 2.8mL
Mass of cube = 30g
Density = Mass / Volume
Density = 30 / 2.8 = 10.71 g/mL
What determines the strength of a dipole-dipole force?
A. The more symmetrical the molecule, the stronger the force.
B. The more hydrogen in the molecule, the stronger the force.
C. The more polar the molecules, the stronger the force.
D. The larger the atomic radius, the stronger the force.
Answers
The more polar the molecules, the stronger the force. Hence, option C is correct.
What is dipole-dipole force?Dipole-Dipole forces are the interaction between molecules of the permanent dipole. It occurs between the partially charged positive molecules and partially charged negative molecules.
Polar molecules align themselves so that the δ– end of one molecule is near the δ+ ends of other molecules.
The molecules are thus attracted to each other. Dipole-dipole forces exist between polar molecules.
The greater the polarity, the stronger the dipole-dipole forces.
Hence, option C is correct.
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What is the chemical equation of a covalent bond
Answers
Answer:
In my knowledge of chemistry, I believe there isn't chemical equation for covalent bond. There is only covalent formula
Explanation:
What are Chemical and Physical Propertys and how do you know which is which???
Answers
Answer:
A physical property is a characteristic of a substance that can be observed or measured without changing the identity of a substance.
A chemical property describes the ability of a substance to undergo a specific chemical change and form new substances.
Explanation:
To know which one is which, just REMEMBER physical property can be observed without changing the original substance, while chemical properties require a change in the original substance, which occurs when the new subtance is formed after undergoing the chemical reaction.
The layers of earth are the crust, mantle, and core, with the core being divided into inner and outer layers. Which of the following does NOT describe the layers of the solid Earth?
A- The core makes up the majority of Earth’s volume
B- The mantle is composed of rocks known as silicates
C- The core is made up of dense elements, such as iron and nickel.
D- The crust is extrememly thin when compared to the core of mantle
Answers
Answer:
C- The core is made up of dense elements, such as iron and nickel.
Can you guys help me out??
I2KI+ Pb(NO3)2---- PbI2+ 2KNO3 is what type of reaction?
* Decomposition
* Replacement
* Synthesis
Answers
The reaction between hydrogen gas and chlorine gas to form hydrogen chloride has reached equilibrium.
H2(g) + Cl2 (g) = 2HCl(g)
What is the effect of adding more hydrogen chloride to the reaction chamber?
Answers
The question is about the effect of adding more hydrogen chloride to the reaction chamber when the reaction between hydrogen gas and chlorine gas to form hydrogen chloride has reached equilibrium, as represented by the equation:
H2(g) + Cl2 (g) = 2HCl(g)
To understand the effect, we'll use Le Chatelier's Principle, which states that when a system in equilibrium is subjected to a change in concentration, temperature, or pressure, the system will shift in a direction that counteracts the change.
Step 1: Identify the change in the system
In this case, more hydrogen chloride (HCl) is added to the reaction chamber.
Step 2: Determine the effect on equilibrium
Adding more HCl increases the concentration of the product, so the reaction will shift in the direction that reduces the concentration of HCl. In this case, it will shift to the left, towards the reactants (H2 and Cl2).
Step 3: Describe the outcome
The effect of adding more hydrogen chloride to the reaction chamber is that the reaction shifts to the left, favoring the formation of hydrogen gas (H2) and chlorine gas (Cl2) to counteract the increase in HCl concentration.
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Why don't we feel the air pressing on us all the time?
Answers
Answer: Why don't we feel the air pressing on us all the time?
Explanation:
Because air is a fluid, the weight of the air is transmitted to the palm of your hand and to the back of your hand at the same time. These forces cancel so that your hand overall feels no net force
Answer:the gravity in the atmosphere is pulling all the air so we can survive
Explanation:
pls help, I will give Brainlist if you answer correct. pls
Answers
Explanation:
The union of vinegar and bicarbonate produces carbon dioxide
The carbonic acid, which is weaker, in turn breaks down into water and carbon dioxide, which being volatile separates
will observe a yellow color, confirming that BASIC HYDROLYSIS has taken place. To the touch the bottle cools and in the end a white deposit may remain on the bottom.
A student adds a tablespoon of sugar to a glass containing tea and ice cubes. The mixture is then stirred until all the sugar dissolves.
Which observation is a clue that the student's final mixture is heterogeneous
A. Some ice cubes are floating in the tea
B. The sugar crystals are no longer visible in the tea
C. The mixture looks the same throughout
D. Some water droplets form on the outside of the glass
The subject is science
Answers
Answer:
The correct option is;
A. Some ice cubes are floating in the tea
Explanation:
A heterogenous mixture is one that is made up of more than one clearly identifiable phase of matter (such as solid and liquid, liquid and gas, gas and solid, or solid, liquid and gas combined) and therefore having non-uniform composition, which varies from one section to another within the mixture.
Ice cubes which are solids being observable on the surface of the mixture provides clue that the student has made an heterogenous mixture.
What kind of protein is albumin?.
Answers
Albumin in a single chain protein and it is family of globular proteins.
What is Albumin ?
The most common protein in blood plasma is albumin. In order to help in the movement of hormones, vitamins, and enzymes throughout the body, it helps in maintaining blood in arteries and veins. The liver produces albumin, which enters the bloodstream quickly.
With a molecular weight of 66/5 kDa with 585 amino acids, albumin is a single-chain protein. It is a simple protein lacking prosthetic groups and a non-glycosylated polypeptide.
The most common albumins are the serum albumins, which belong to a family of globular proteins. In addition to being moderately soluble in concentrated salt solutions and being heat denaturable, all albumin family proteins are water-soluble.
Thus, we can state that, albumin is a single chain protein.
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Direction: Read each situation in the table below, then state if it is a density-independent limiting factor or a density-depent limiting factor. Indicate the specific limiting factor that is occuring.
☞︎︎︎Please help me☜︎︎︎
❌NONSENSE➪ REPORT❌
Answers
Answer:
1. Dependent, carrying capacity
2. Dependent, dinoflaggelates
3. Independent, oil spill
4. Dependent, virus
5. Independent, typhoon
6. Independent, deforestation
7. Dependent, predation
8. Dependent, human exploitation
9. Dependent, virus
10. Independent, oxygen depletion
Explanation:
Arrange the gases from most dense to least dense at a given temperature and pressure.
Most dense
Least dense
Answer Bank
Ar
Ne
CO2
H
C12
Answers
Answer:
Arrange them in order of greatest to least Molar Mass to get most dense to least dense at a given temperature and pressure.
Explanation:
"Given Temperature and Pressure" just tells you that those two variables are being held constant. The Ideal Gas Law (PV = nRT) shows that n (the # of moles) and V (the volume) are variable still. To keep pressure constant, we need to increase the volume so that the force per area is the same which would unfortunately lower the density. The only way for a gas to have the greatest density would be to have the least average kinetic energy to keep the pressure constant at a smaller volume. This is because kinetic energy is equal to KE = 1/2 m v^2, where m is mass in kilograms and v is the velocity. IT IS CRUCIAL TO NOTE THAT ACCORDING TO KINETIC MOLECULAR THEORY, ALL GASES HAVE THE SAME AVG. KINETIC ENERGY WHEN AT THE SAME TEMPERATURE. So since the avg. KE is also constant across these answers due to the temp. being constant, our only way to decrease the velocity (the rate at which the particles are moving per second) and in turn the number of collisions (to repeat, a smaller number of collisions is desired because they are equal to the pressure that must maintained at a constant value at the smallest volume possible to achieve highest density possible) is to increase the molar mass. This is also pretty intutive for the other part of the issue: since Density is a broken heart (m/v), a higher molar mass would ensure a smaller pressure (due to decreased velocity) and smaller volume (due to constant pressure). Okay, now order the gases heaviest to lightest in terms of molar mass and you got your answer. Please gimme brainliest if this helped bc it took 15 minutes to type out. Hope this helped you! :D
Density is an intensive property as it does not depend on the quantity of the substances Whereas mass and volume are extensive property. The order of density is carbon dioxide>Neon >argon>carbon-12> hydrogen.
What is density?Density tells about the compactness of the substances, how much dense is the substances in other words. Object that is more denser than water they just sink in the water.
Mathematically,
Density of gas = Molar Mass of the gas ÷volume occupied by the given gases
Density is directly proportional to molar mass of the gases.
Molar mass of argon = 18g/mole
Molar mass of Neon = 20g/mole
Molar mass of carbon dioxide=44.01 g/mol
Molar mass of hydrogen=1g/mol
Molar mass of carbon-12=12g/mol
The order of gases from most dense to least dense at a given temperature and pressure is carbon dioxide>Neon >argon>carbon-12> hydrogen.
Therefore, the order of density is carbon dioxide>Neon >argon>carbon-12> hydrogen.
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In the following nuclear equation for alpha decay, what is the
missing subscript that will balance the equation?
228U
234Th + He + Energy
92
a 92
b 88
C 94
d 90
Answers
The missing subscript that will balance the equation is 92.
The given Radioactive decay chemical equation is,
²³⁴U → ²³⁰Th₉₀ + ⁴He₂ + Energy
In the above reaction, the Uranium atom is decayed into the Thorium atom and a helium nucleus is released from Uranium along with energy.
When a bigger atom is unstable, it decays into smaller stable atoms by radioactive decay, one such decay is Alpha Decay.
In Alpha Decay, the mass number of the decaying particle gets reduced by four units and the atomic number of the decaying particle reduces by two. i.e. A helium nucleus is released from the the particle.
So the atomic of the not decayed uranium will be 2 more then the atomic number of thorium.
So, our balanced reaction will be,
²³⁴U₉₂ → ²³⁰Th₉₀ + ⁴He₂ + Energy.
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how do calcium and fluorine become stable when they form calcium fluoride?
Answers
Answer:
Explanation:
It occurs as the mineral fluorite (also called fluorspar), which is often deeply coloured owing to impurities. ... Calcium reacts with fluorine to form the compound CaF2. ... (lead is very close) as hydrogen the bond would be considered ionic! ... What is the most stable monatomic ion formed from nitrogen?
Answer:
CaF2 is stable when it is formed because Ca loses two of its electrons. Both accept one electron each. now the Calcium is satisfied because it lost its two electrons and is now behaving like a noble gas, which is what they all want to be like The Flourine is satisfied because they both gained one electron, allowing them to have 8 valence electrons also like a noble gas.
The key is in the 8 valence electrons! Ca has to lose two to have 8, and F has to gain one to have 8fluorinefluorines...
Explanation:
What would happen if the amount of sodium azide used was far greater or far less thanIts 1424 grams of sodium azide which is required to produce 736 L of Nitrogen gas with the density of 1.25 g/LIts
Answers
Based on the stoichiometry of the reaction, If the mass of sodium azide used was far greater than 1424 g, the volume of nitrogen gas produced will be far greater than 736 L.
However, If the mass of sodium azide used was far less than 1424 g, the volume of nitrogen gas produced will be far less than 736 L.
What is sodium azide used for?Sodium azide is the chemical found in automobile airbags.
Automotive air bags inflate when an electrical charge triggered by automobile impact causes sodium azide, NaN3, to rapidly decompose to its component elements, nitrogen gas and sodium
The equation of the reaction is given below:
2 NaN3(s) → 2 Na(s) + 3 N2(g)According to the equation of reaction, 2 moles of sodium azide produces 3 moles of nitrogen gas.
1 mole of Nitrogen gas has a volume of 22.4 L
Molar mass of sodium azide is 65 g
Moles of sodium azide in 1424 g = 1424/65 = 21.9077 moles
21.9077 moles of sodium azide will produce 21.9077 * 3/2 moles of nitrogen gas = 32.86 moles of nitrogen gas
32.86 moles of nitrogen gas will occupy a volume of 32.86 * 22.4 = 736 L
If the mass of sodium azide used was far greater than 1424 g, the volume of nitrogen gas produced will be far greater than 736 L.
If the mass of sodium azide used was far less than 1424 g, the volume of nitrogen gas produced will be far less than 736 L.
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Forty liters of a 60% salt solution is being diluted to a 45% salt solution. how much of the solution must be drained and replaced with distilled water to get forty liters of a 45% salt solution?
Answers
Based on the given data, 10 liters of the 60% salt solution must be drained and replaced with distilled water to get 40 liters of a 45% salt solution.
Dilution of Salt SolutionTo determine the amount of a 60% salt solution that needs to be drained and replaced with distilled water to achieve a 45% salt solution, we can use a simple mathematical calculation. First, let's denote the amount of solution to be drained and replaced with distilled water as "x". The concentration of salt in the solution after the dilution can be calculated as the sum of the concentration of the original solution and the dilution solution, which is x liters of distilled water with a 0% salt concentration.
Next, we can set up an equation to solve for x using the known information: (40 - x) * 0.60 + x * 0.00 = 40 * 0.45. Solving for x, we find that 0.60x = 6, and x = 10. This means that 10 liters of the original 60% salt solution must be drained and replaced with distilled water to achieve 40 liters of a 45% salt solution.
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Which is the correct statement? *
O the nucleus has no mass and has a positive charge
O the nucleus has more mass than the electrons and has a negative charge
the nucleus has less mass than the electrons and has a negative charge.
O the electrons have less mass than the nucleus and have a negative charge
Answers
The statement "the electrons have less mass than the nucleus and have a negative charge" is correct.
What are electrons?Subatomic particles with a negative electric charge are known as electrons. They exist beyond the atomic nucleus, in the electron cloud or electron shell, and are critical to atoms' chemical function.
Electrons are extremely small and light, having a mass of around 9.11 x 10^-31 kg, and they may be found in practically any substance. They are also involved in the transmission of electrical charge and the production of chemical bonds, making them vital to many natural and modern-day activities.
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Takes off one amino acid from the -COOH side of a peptide chain Glucoamylase Aminopeptidase Takes off one amino acid from the amine side of a peptide chain Lactase Carboxypeptidase Brush-border enzyme that is vital to the digestion of breast milk Salivary amylase Acidophilic enzyme that cleaves all peptide bonds between tyrosine and phenylalanine Deoxyribonuclease Popsin Acidic compound that activatos pepsinogen
Answers
The acidic cοmpοund that activates pepsinοgen is hydrοchlοric acid (HCl).
What is an acidic cοmpοund?An acidic cοmpοund is a substance that can release hydrοgen iοns (H+) when dissοlved in water, resulting in an increase in the cοncentratiοn οf H+ iοns and a decrease in pH. Examples οf acidic cοmpοunds include hydrοchlοric acid (HCl), sulfuric acid (H₂SO₄), acetic acid (CH₃COOH), and citric acid (C₆H₈O₇).
Takes οff οne aminο acid frοm the -COOH side οf a peptide chain: Carbοxypeptidase
Takes οff οne aminο acid frοm the amine side οf a peptide chain: Aminοpeptidase
Brush-bοrder enzyme that is vital tο the digestiοn οf breast milk: Lactase
Salivary amylase: Enzyme fοund in saliva that breaks dοwn starch intο smaller sugars
Acidοphilic enzyme that cleaves all peptide bοnds between tyrοsine and phenylalanine: Pepsin
Deοxyribοnuclease: Enzyme that breaks dοwn DNA intο smaller fragments
Pepsinοgen: Inactive precursοr fοrm οf pepsin, which is activated by an acidic cοmpοund called hydrοchlοric acid (HCl) in the stοmach.
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a buffer consists of equal concentrations of hf and . what happens to the ratio of actually in solution as a strong base, , is added to the equilibrium?
Answers
When a strong base is added to a buffer solution containing equal concentrations of a weak acid and its conjugate base, the equilibrium of the buffer shifts towards the conjugate base, and the ratio of weak acid to conjugate base changes.
A buffer solution consists of a weak acid (HF) and its conjugate base (F-). When a strong base, such as NaOH, is added to the buffer solution, the base will react with the weak acid to produce more of its conjugate base and less of the weak acid. This will shift the equilibrium of the buffer towards the conjugate base and increase the concentration of the F- ion in the solution.
However, the buffer is designed to resist changes in pH, so the effect of the added base will be somewhat limited. The buffer will work to restore the original pH by reacting with some of the added base to produce more of the weak acid. As a result, the ratio of the weak acid to its conjugate base will change, but the change will be relatively small.
The key feature of a buffer solution is its ability to resist changes in pH, so even though the ratio of weak acid to conjugate base will change, the overall pH of the solution will change only slightly. This makes buffer solutions useful for maintaining a stable pH in a wide range of applications, such as biological systems and chemical processes.
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solid nacl is produced by the reaction of metallic sodium with chlorine gas. which equation shows this reaction?
Answers
Answer:
Na (s) + Cl2 (g) → NaCl (s)
A thermometer is taken from a room where the temperature is 24
∘
C to the outdoors, where the temperature is −11
∘
C. After one minute the thermometer reads 7
∘
C. (a) What will the reading on the thermometer be after 4 more minutes? (b) When will the thermometer read −10
∘
C ? minutes after it was taken to the outdoors.
Answers
The thermometer will read -10°C after about 2.43 minutes.
(a) After four more minutes, the thermometer will read -1°C.
This is because the temperature difference between the room and outdoors is (24 - (-11)) = 35°C.
The thermometer then rises 7°C in one minute, so the thermometer is heated at 7°C/minute, i.e. 35°C in five minutes.
So the temperature of the thermometer after 4 more minutes is 7°C + 7°C + 7°C + 7°C = 28°C, 28°C - 35°C = -7°C, -7°C - 3°C = -10°C.
Thus the reading on the thermometer will be -1°C after four more minutes.
(b) To find out when the thermometer will read -10°C, use the formula:
time = (temperature difference ÷ heating rate) + time to start
= (-10°C - 7°C) ÷ 7°C/minute + 1 minute
= -17°C ÷ 7°C/minute + 1 minute≈ -2.43 minutes
Thus, the thermometer will read -10°C after about 2.43 minutes.
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Determine the amount of energy absorbed by 2.00 L of gasoline as it is converted to the vapor phase at its boiling point.
Answers
The amount of energy absorbed by 2.00 L of gasoline as it is converted to the vapor phase at its boiling point is 22606 J.
What is enthalpy of vaporization?We know that;
1 mole of gasoline occupies 22.4 L
x moles of gasoline occupies 2 L
x = 0.089 moles
Then we have that the mass of the gasoline = 0.089 moles * 100 g/mol
= 8.9 g
Then;
H = mL
L = 2540 J/g for gasoline
Thus the energy that is absorbed is;
H = 8.9 g * 2540 J/g
H = 22606 J
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