Chemistry Third Quarter Exam Review One 3-15-13
1. Determine the % composition of the following:
- Ammonium oxalate
- Magnesium hydroxide
- Sodium phosphate
2. Using your answers from problem 2 calculate the number of grams of these
elements:
- Nitrogen, hydrogen, carbon and oxygen in 25g of ammonium oxalate
- Magnesium and oxygen and hydrogen in 97.4g magnesium oxide
- Phosphorous, sodium and oxygen in 804g of sodium phosphate
3. Calculate the empirical formula for the following compounds:
- 36.1% Ca, 63.9% Cl
- 3.7% H, 44.4% C, 51.9% N
4. A compound is found to have 1.121 g nitrogen, 0.161 g hydrogen, 0.480 g carbon
and 0.640 g oxygen. What is its empirical formula?
5. Find the empirical and molecular formulas for the compounds given below.
a. 51.28 percent C, 9.40 percent H, 27.35 percent O, 11.97 percent N,
experimental molar mass =234
b. 33.18 percent C, 4.60 percent H, 29.49 percent O, 32.72 percent Cl,
experimental molar mass=108.5
6. What is the molecular formula for each of the following compounds? The
empirical and experimental masses are given.
a. CH2O 90g/mol
b. HgCl 472.2g/mol
7. Write the balanced chemical equations for the following:
- sulfur dioxide and oxygen react to form sulfur trioxide
- iron III oxide and hydrogen react to form iron metal and water
- phosphorus and oxygen react to form tetraphosphorous decaoxide
8. Identify the kind of reaction, then balance the following equations:
- KOH + H2CO3 H2O + K2CO3
- C4H8O2 + O2 H2O + CO2
- Mg(OH)2 + H3PO4 -H2O + Mg3(PO4 )2
- HNO3 + Ni -Ni(NO3)2 + _____ H2
- Ba(HCO3)2 -BaCO3 + H2O + CO2
9. ID the type of reaction in each of the following then complete and write the
balanced equations for each:
- phosphoric acid and magnesium hydroxide react
- hydrochloric acid and sodium hydroxide react
- sodium and oxygen react
10. Write the balanced equation for each of the following reactions, then interpret
them in terms of numbers of atoms, molecules, moles, mass and volume (assume
all reactants and products are gases):
- Write the balanced equation for the production of water.
- Acetylene (C2H2) combusts
11. Calculate the following quantities in L:
- 6.67 mol nitrogen
- 12.87 mol oxygen
12. Calculate the following quantities in mol:
- 456L of fluorine
- 212 L of hydrogen
13. Calculate the following quantities in grams:
- 342 L of oxygen
- .23L of hydrogen