Question 1

Which of the following is true about the actual yield of a product?

Accepted Answer

The actual yield of a product is almost always less than the theoretical yield due to experimental errors, incomplete reactions, and other factors.

Question 2

The reaction of 5.07 g N₂ with 0.722 g H₂ produces 1.27 g NH₃.The percent yield of this reaction is ________.

Accepted Answer

The answer of The reaction of 5.07 g N₂ with...

Question 3

Phosphorus trichloride,PCl₃,can be produced from the reaction below: P₄(s)+ 6 Cl₂(g)→ 4 PCl₃(g) If 1.00 g of phosphorus,P₄,reacts with 1.00 g of chlorine,Cl₂,which reactant is the limiting reactant and what mass of product may be produced?

Accepted Answer

The answer of Phosphorus trichloride,PCl₃,can be produced from the reaction...

Question 4

In combustion analysis,the gases produced by the combustion of a hydrocarbon are passed through a tube containing finely divided sodium hydroxide supported on asbestos.The purpose of the sodium hydroxide is to absorb ________ produced by the combustion reaction.

Accepted Answer

The answer of In combustion analysis,the gases produced by the...

Question 5

The following equation: A = ε ×  × C (where  is path length and C is concentration)is known as the _____-Lambert law.

Accepted Answer

The answer of The following equation: A = ε ×...

Question 6

The percent yield of a chemical reaction is calculated by dividing the actual yield by the ________ yield and multiplying by 100%.

Accepted Answer

The answer of The percent yield of a chemical reaction...

Question 7

The pH of purified water (or of a neutral solution)is _____.

Accepted Answer

The answer of The pH of purified water (or of...

Question 8

Calibration of a spectrophotometer using a series of green dye containing solutions provides a set of data which follows the Beer-Lambert Law,with a trendline of y = 1.398 × 10³x (y-axis = absorbance,x-axis = molar concentration).What is the molar concentration of a solution with an absorbance of 0.8427?

Accepted Answer

To find the molar concentration (x) for an absorbance (y) of 0.8427 using the given trendline equation y = 1.398 × 10^1 x, rearrange the equation to solve for x: x = y / (1.398 × 10^1). Substituting the given absorbance value, x = 0.8427 / 13.98 = 0.6028 M.

Question 9

A solution of sodium oxalate (Na₂C₂O₄)in acidic solution is titrated with a solution of potassium permanganate (KMnO₄)according to the following balanced chemical equation: 2KMnO₄(aq)+ 8H₂SO₄(aq)+ 5Na₂C₂O₄(aq)→ 2MnSO₄(aq)+ 8H₂O(l)+ 10CO₂(g)+ 5Na₂SO₄(aq)+ K₂SO₄(aq) What volume of 0.0206 M KMnO₄ is required to titrate 0.176 g of Na₂C₂O₄ dissolved in 50.0 mL of solution?

Accepted Answer

First, we need to calculate the number of moles of Na2C2O4:
moles Na2C2O4 = 0.176 g / (2 * 23.00 + 12.01 + 4 * 16.00) = 0.001 mol

Next, we can use stoichiometry to determine how many moles of KMnO4 are required to react with the Na2C2O4:
2 KMnO4 + 5 Na2C2O4 + 8 H2SO4 → 2 MnSO4 + 10 CO2 + 8 H2O + 5 Na2SO4 + K2SO4

From the balanced equation, we can see that 2 moles of KMnO4 react with 5 moles of Na2C2O4. Therefore, the number of moles of KMnO4 needed is:

moles KMnO4 = (0.001 mol Na2C2O4) / (5 mol Na2C2O4 / 2 mol KMnO4) = 0.0004 mol KMnO4

Finally, we can use the molarity and volume of the KMnO4 solution to determine the volume required for the titration:

moles KMnO4 = M KMnO4 x V KMnO4
V KMnO4 = moles KMnO4 / M KMnO4 = 0.0004 mol / 0.0206 M = 0.0194 L = 19.4 mL

Therefore, the best choice is C) 25.5 mL, which is the closest to the calculated volume of KMnO4 required for the titration.

Question 10

The reaction of HCl with NaOH is represented by the equation HCl(aq)+ NaOH(aq)→ NaCl(aq)+ H₂O(l) What volume of 0.614 M HCl is required to titrate 18.8 mL of 0.619 M NaOH?

Accepted Answer

First, we need to use stoichiometry to find the amount of HCl needed to neutralize the NaOH. From the balanced equation, we can see that 1 mole of HCl reacts with 1 mole of NaOH to produce 1 mole of NaCl and 1 mole of water:

HCl(aq) + NaOH(aq) → NaCl(aq) + H2O(l)

We can use the following formula to calculate the moles of NaOH that were used:

moles NaOH = Molarity × Volume (in liters)
          = 0.619 M × 0.0188 L
          = 0.01163 mol

Since the reaction is 1:1, we know that the moles of HCl required is also 0.01163 mol.

Now we can use the molarity and the moles of HCl to calculate the volume needed:

moles HCl = Molarity × Volume (in liters)
Volume (in liters) = moles HCl ÷ Molarity
Volume (in liters) = 0.01163 mol ÷ 0.614 M
Volume (in liters) = 0.01894 L = 19.0 mL

Therefore, the correct answer is C) 19.0 mL.

Question 11

The numbers preceding the formulas in chemical equations are referred to as the _____ coefficients.

Accepted Answer

The answer of The numbers preceding the formulas in chemical...

Question 12

An unknown diprotic acid (H₂A)requires 31.81 mL of 0.109 M NaOH to completely neutralize a 0.685 g sample.Calculate the approximate molar mass of the acid.

Accepted Answer

First, we need to determine the moles of NaOH used:
0.03181 L x 0.109 mol/L = 0.00347 mol NaOH

Since the acid is diprotic, it will require two moles of NaOH to neutralize one mole of the acid. Therefore, the moles of acid can be calculated as:

0.00347 mol NaOH x (1 mol acid / 2 mol NaOH) = 0.00174 mol acid

To find the molar mass of the acid, we can use the formula:

Molar mass = mass / moles

The mass of the acid is given as 0.685 g, so:

Molar mass = 0.685 g / 0.00174 mol = 394.8 g/mol

Rounding to the nearest whole number gives us an approximate molar mass of 395 g/mol, which corresponds to choice B.

Question 13

Molarity is defined as the _____.

Accepted Answer

Molarity is a measure of the concentration of a solute in a solution, defined as the amount of solute (in moles) per liter of solution. Option B correctly defines molarity as the amount of solute per liter of solution.

Question 14

If 0.1800 g of impure soda ash (Na₂CO₃)is titrated with 15.66 mL of 0.1082 M HCl,what is the percent purity of the soda ash? Na₂CO₃(aq)+ 2 HCl(aq)→ 2 NaCl(aq)+ H₂O( )+ CO₂(g)

Accepted Answer

The answer of If 0.1800 g of impure soda ash...

Question 15

A 30.00-mL sample of a weak monoprotic acid is titrated with 0.0915 M NaOH.At the endpoint,it is found that 45.98 mL of titrant was used.What was the concentration of the weak acid?

Accepted Answer

First, we need to determine the moles of NaOH used:
moles NaOH = M NaOH x volume NaOH = 0.0915 M x 45.98 mL / 1000 mL/L = 0.00420 mol
Then, we can use the balanced chemical equation for the reaction between the weak acid and NaOH to determine the moles of weak acid present:
weak acid + NaOH → salt + water
1 mol 1 mol
0.00420 mol NaOH x 1 mol weak acid / 1 mol NaOH = 0.00420 mol weak acid
Finally, we can calculate the concentration of the weak acid using the volume of the sample and the moles of weak acid:
M weak acid = moles weak acid / volume sample = 0.00420 mol / 30.00 mL / 1000 mL/L = 0.140 M

Therefore, the best choice is A as it is the calculated concentration of the weak acid.

Question 16

An impure sample of benzoic acid (C₆H₅COOH,122.12 g/mol)is titrated with 0.5360 M NaOH.A 1.888-g sample requires 20.50 mL of titrant to reach the endpoint.What is the percent by mass of benzoic acid in the sample? C₆H₅COOH(aq)+ NaOH(aq)→ NaC₆H₅COO(aq)+ H₂O(l)

Accepted Answer

To find the percent by mass of benzoic acid, first calculate the moles of NaOH used: 0.5360 M * 0.02050 L = 0.010988 mol. Since the reaction is 1:1, moles of benzoic acid = 0.010988 mol. Mass of benzoic acid = 0.010988 mol * 122.12 g/mol = 1.340 g. Percent by mass = (1.340 g / 1.888 g) * 100% = 71.06%.

Question 17

Which of the following is the correct representation for absorbance of a sample?

Accepted Answer

Absorbance (A) of a sample is defined as the negative logarithm (base 10) of the transmittance (T) of a sample. Therefore, the correct representation is A = -log T.

Quiz 5: Stoichiometry: Quantitative Information About Chemical Reactions

Which of the following is true about the actual yield of a product?

The reaction of 5.07 g N₂ with 0.722 g H₂ produces 1.27 g NH₃.The percent yield of this reaction is ________.

Phosphorus trichloride,PCl₃,can be produced from the reaction below: P₄(s)+ 6 Cl₂(g)→ 4 PCl₃(g) If 1.00 g of phosphorus,P₄,reacts with 1.00 g of chlorine,Cl₂,which reactant is the limiting reactant and what mass of product may be produced?

In combustion analysis,the gases produced by the combustion of a hydrocarbon are passed through a tube containing finely divided sodium hydroxide supported on asbestos.The purpose of the sodium hydroxide is to absorb ________ produced by the combustion reaction.

The following equation: A = ε × × C (where is path length and C is concentration)is known as the _____-Lambert law.

The percent yield of a chemical reaction is calculated by dividing the actual yield by the ________ yield and multiplying by 100%.

The pH of purified water (or of a neutral solution)is _____.

The reaction of HCl with NaOH is represented by the equation HCl(aq) + NaOH(aq) → NaCl(aq) + H₂O(l) What volume of 0.614 M HCl is required to titrate 18.8 mL of 0.619 M NaOH?

The numbers preceding the formulas in chemical equations are referred to as the _____ coefficients.

An unknown diprotic acid (H₂A) requires 31.81 mL of 0.109 M NaOH to completely neutralize a 0.685 g sample.Calculate the approximate molar mass of the acid.

Molarity is defined as the _____.

If 0.1800 g of impure soda ash (Na₂CO₃) is titrated with 15.66 mL of 0.1082 M HCl,what is the percent purity of the soda ash? Na₂CO₃(aq) + 2 HCl(aq) → 2 NaCl(aq) + H₂O( ) + CO₂(g)

A 30.00-mL sample of a weak monoprotic acid is titrated with 0.0915 M NaOH.At the endpoint,it is found that 45.98 mL of titrant was used.What was the concentration of the weak acid?

An impure sample of benzoic acid (C₆H₅COOH,122.12 g/mol) is titrated with 0.5360 M NaOH.A 1.888-g sample requires 20.50 mL of titrant to reach the endpoint.What is the percent by mass of benzoic acid in the sample? C₆H₅COOH(aq) + NaOH(aq) → NaC₆H₅COO(aq) + H₂O(l)

Which of the following is the correct representation for absorbance of a sample?

Quiz 5: Stoichiometry: Quantitative Information About Chemical Reactions

Which of the following is true about the actual yield of a product?

The reaction of 5.07 g N2 with 0.722 g H2 produces 1.27 g NH3.The percent yield of this reaction is ________.

Phosphorus trichloride,PCl3,can be produced from the reaction below: P4(s)+ 6 Cl2(g)→ 4 PCl3(g) If 1.00 g of phosphorus,P4,reacts with 1.00 g of chlorine,Cl2,which reactant is the limiting reactant and what mass of product may be produced?

In combustion analysis,the gases produced by the combustion of a hydrocarbon are passed through a tube containing finely divided sodium hydroxide supported on asbestos.The purpose of the sodium hydroxide is to absorb ________ produced by the combustion reaction.

The following equation: A = ε × × C (where is path length and C is concentration)is known as the _____-Lambert law.

The percent yield of a chemical reaction is calculated by dividing the actual yield by the ________ yield and multiplying by 100%.

The pH of purified water (or of a neutral solution)is _____.

The reaction of HCl with NaOH is represented by the equation HCl(aq) + NaOH(aq) → NaCl(aq) + H2O(l) What volume of 0.614 M HCl is required to titrate 18.8 mL of 0.619 M NaOH?

The numbers preceding the formulas in chemical equations are referred to as the _____ coefficients.

An unknown diprotic acid (H2A) requires 31.81 mL of 0.109 M NaOH to completely neutralize a 0.685 g sample.Calculate the approximate molar mass of the acid.

Molarity is defined as the _____.

If 0.1800 g of impure soda ash (Na2CO3) is titrated with 15.66 mL of 0.1082 M HCl,what is the percent purity of the soda ash? Na2CO3(aq) + 2 HCl(aq) → 2 NaCl(aq) + H2O( ) + CO2(g)

A 30.00-mL sample of a weak monoprotic acid is titrated with 0.0915 M NaOH.At the endpoint,it is found that 45.98 mL of titrant was used.What was the concentration of the weak acid?

An impure sample of benzoic acid (C6H5COOH,122.12 g/mol) is titrated with 0.5360 M NaOH.A 1.888-g sample requires 20.50 mL of titrant to reach the endpoint.What is the percent by mass of benzoic acid in the sample? C6H5COOH(aq) + NaOH(aq) → NaC6H5COO(aq) + H2O(l)

Which of the following is the correct representation for absorbance of a sample?

The reaction of 5.07 g N₂ with 0.722 g H₂ produces 1.27 g NH₃.The percent yield of this reaction is ________.

Phosphorus trichloride,PCl₃,can be produced from the reaction below: P₄(s)+ 6 Cl₂(g)→ 4 PCl₃(g) If 1.00 g of phosphorus,P₄,reacts with 1.00 g of chlorine,Cl₂,which reactant is the limiting reactant and what mass of product may be produced?

The reaction of HCl with NaOH is represented by the equation HCl(aq) + NaOH(aq) → NaCl(aq) + H₂O(l) What volume of 0.614 M HCl is required to titrate 18.8 mL of 0.619 M NaOH?

An unknown diprotic acid (H₂A) requires 31.81 mL of 0.109 M NaOH to completely neutralize a 0.685 g sample.Calculate the approximate molar mass of the acid.

If 0.1800 g of impure soda ash (Na₂CO₃) is titrated with 15.66 mL of 0.1082 M HCl,what is the percent purity of the soda ash? Na₂CO₃(aq) + 2 HCl(aq) → 2 NaCl(aq) + H₂O( ) + CO₂(g)

An impure sample of benzoic acid (C₆H₅COOH,122.12 g/mol) is titrated with 0.5360 M NaOH.A 1.888-g sample requires 20.50 mL of titrant to reach the endpoint.What is the percent by mass of benzoic acid in the sample? C₆H₅COOH(aq) + NaOH(aq) → NaC₆H₅COO(aq) + H₂O(l)