General Chemistry Answers

A saline solution is prepared by dissolving 5.04 g of NaCl in 95.0 g of water.

Calculate the following:

a. Mole fraction of the solute and the solvent

b. % mass of the solute

c. Concentration of solution in ppm

Please put what letter did you answer in every solution

Percent Composition and Empirical Formula

1. The chemical analysis of aspirin indicates that the molecule is 60.00% carbon, 4.44% hydrogen,

and 35.56% oxygen. Determine the empirical formula for aspirin.

2. **Glucose is a simple sugar produced during photosynthesis. It has a molecular formula of C6H12O6.

a. Compute for the percent composition.

b. Determine the empirical formula.

Percent Composition and Empirical Formula

1. Phosphoric acid (H3PO4) is a colorless, syrupy liquid used in detergents, fertilizers, toothpastes,

and in carbonated beverages for a “tangy” flavor. Calculate the percent composition by mass of H, P,

and O in this compound.

2. Propane is hydrocarbon, a compound composed only of carbon and hydrogen. It is 81.82%

carbon and 18.18% hydrogen. What is the empirical formula?

Solve the following stoichiometry grams-grams problems:

1) Using the following equation:

Pb(SO4)2 + 4 LiNO3 

Pb(NO3)4 + 2 Li2SO4

How many grams of lithium nitrate will be needed to make 250 grams of lithium sulfate,

assuming that you have an adequate amount of lead (IV) sulfate to do the reaction?

2) Using the following equation:

Fe2O3 + 3 H2 -------------> 2 Fe + 3 H2O

Calculate how many grams of iron can be made from 16.5 grams of Fe2O3 by the following

equation.

Solve the following stoichiometry grams-grams problems:

1) The combustion of a sample of butane, C4H10 (lighter fluid), produced 2.46 grams of water.

2 C4H10 + 13O2 -------> 8CO2 + 10H2O

(a) How many moles of water formed?

(b) How many moles of butane burned?

(c) How many grams of butane burned?

(d) How much oxygen was used up in moles?

(e) How much oxygen was used up in grams?

2) Using the following equation:

2 NaOH + H2SO4  2 H2O + Na2SO4

How many grams of sodium sulfate will be formed if you start with 200 grams of sodium

hydroxide and you have an excess of sulfuric acid?

Convert the following number of moles into their corresponding number of particles.

10. 0.0455 moles of hydrochloric acid

11. 1.2 moles of glucose (C6H12O6)

12. 0.32 moles of sodium bicarbonate

Convert the following masses into their corresponding number of moles.

6. 23.5 g of sodium chloride

7. 0.778 g of sodium cyanide

8. 0.250 g of water

9. 169.45 g of calcium acetate

10. 79.9 g of potassium permanganate

Convert the following number of moles of chemical into its corresponding mass in grams.

1. 0.436 moles of ammonium chloride

2. 2.360 moles of lead (II) oxide

3. 0.031 moles of aluminium iodide

4. 1.077 moles of magnesium phosphate

5. 0.50 moles of calcium nitrate

Compute for answer of these and round your final answer following the rules of significant figures.

1. 1567.00829 x 17.0812

2. 145.9807 + 12.98563

3. 10986.074957 - 450.219

4. 5.0008 x 3.4875231

B.

Covert the following values:

1.

35 oC to oF

2.

238 oF to K

3. 475 K to oF

4. 32 oC to K

Calculate the standard enthalpy of formation of carbon disulfide (CS2) from

its elements, given that

C(graphite) + O2(g) ⟶ CO2(g) ∆H°rxn = - 393.5 kJ/mol

S(rhombic) + O2(g) ⟶ SO2(g) ∆H°rxn = - 296.4 kJ/mol

CS2 (l) + 3O2(g) ⟶ CO2(g) + 2SO2(g) ∆H°rxn = - 1073.6 kJ/mol