## Stoichiometery Quiz (with grading outlined)

1. What is the definition of “moles?” How do you calculate moles in general (Write an equation)? (2 points – 1 point for each question)

(b) Students can either respond in form of equation or writing. The answer must include moles per gram and total grams in order to receive full credit. (1 point)

2. Which of the following has the largest molecular weight? (show your work) (4 points)

a. H2CO3

b. CH3CO2H

c. CH3OH

d. CH3CH2OH

3. Which of the molecules above has the largest mass of carbon per gram? (2 points)

a. H2CO3

b. CH3CO2H

c. CH3OH

d. CH3CH2OH

4. Balance the following reactions and draw an illustration of sodium (Na) Chloride (Cl) in terms of their stoichiometry. (4 points)

Na + Cl2 ---> NaCl

5. (10 points) Baking soda (NaHCO3) is often used as an antacid. It neutralizes excess hydrochloric acid secreted by the stomach:

NaHCO3(s) + HCl(aq) ---> NaCl (aq) + H2O (l) + CO2 (aq)

Milk of magnesia, which is an aqueous suspension of magnesium hydroxide, is also used as an antacid:

Mg(OH)2 (s) + 2HCl (aq) ---> 2H2O (l) + MgCl2 (aq)

Which is the more effective antacid per gram, NaHCO3 or Mg(OH)2? (Show your works)

(2). Full credit if the students have the correct answer. (2 points)

(3). Students may receive half of the credit if they have the setup correct but not the math. No credit will be given if the students have the correct answer but no work is shown. (2 points)

(4). Students may receive half of the credit if they have the setup correct but not the math. No credit will be given if the students have the correct answer but no work is shown. (2 points)

(5). Full credit if the students have the correct answer. (2 points)

**Grading**: (a) If the students include any two of the underlined words (unit, amount, 6.02 x 10^23, atoms), they may receive full credits. If only one term is given, the students will receive half of the credit. (1 point)(b) Students can either respond in form of equation or writing. The answer must include moles per gram and total grams in order to receive full credit. (1 point)

2. Which of the following has the largest molecular weight? (show your work) (4 points)

a. H2CO3

b. CH3CO2H

c. CH3OH

d. CH3CH2OH

**Grading**: Students must show their work in order to receive the full credits. If they have the setup correct, but their math is wrong, they may receive 3/4 credit.3. Which of the molecules above has the largest mass of carbon per gram? (2 points)

a. H2CO3

b. CH3CO2H

c. CH3OH

d. CH3CH2OH

**Grading**: Students may receive full credit if they have the setup correctly. No penalty will be given if the students have the math wrong.4. Balance the following reactions and draw an illustration of sodium (Na) Chloride (Cl) in terms of their stoichiometry. (4 points)

Na + Cl2 ---> NaCl

**Grading**: either forms will be accepted. As long as the student understands that the ratio of sodium to chloride is 1:1.5. (10 points) Baking soda (NaHCO3) is often used as an antacid. It neutralizes excess hydrochloric acid secreted by the stomach:

NaHCO3(s) + HCl(aq) ---> NaCl (aq) + H2O (l) + CO2 (aq)

Milk of magnesia, which is an aqueous suspension of magnesium hydroxide, is also used as an antacid:

Mg(OH)2 (s) + 2HCl (aq) ---> 2H2O (l) + MgCl2 (aq)

Which is the more effective antacid per gram, NaHCO3 or Mg(OH)2? (Show your works)

**Grading:**(1). Students may receive half of the credit if they have the setup correct but not the math. No credit will be given if the students have the correct answer but no work is shown. (2 points)(2). Full credit if the students have the correct answer. (2 points)

(3). Students may receive half of the credit if they have the setup correct but not the math. No credit will be given if the students have the correct answer but no work is shown. (2 points)

(4). Students may receive half of the credit if they have the setup correct but not the math. No credit will be given if the students have the correct answer but no work is shown. (2 points)

(5). Full credit if the students have the correct answer. (2 points)