Unit 1 HW: Stoichiometry

1.

How many moles of sodium are present in 15.6 grams of sodium sulfate?

2.

Calculate the mass (in grams) of nitrate ions in 27.0mL of a 0.15M aqueous solution of aluminum nitrate?

3.

Calculate the percentage of carbon present in C5H14N2 to 4 sig-figs.

4.

You are setting up a reaction between two chemicals that react according to the equation
3 A + 4 B ---> products
If you start with 1.00 mole each of both A and B, which chemical will be in excess at the end, and by how much?

5.

CO2 exhaled by astronauts is removed from the spaceship atmosphere by reaction with KOH
CO2 + 2 KOH —> K2CO3 + H2O
How many liters (at standard conditions) of CO2 can be removed with 2.00 Kg of KOH?

6.

Aluminum and oxygen react according to the following equation
4 Al + 3 O2 —> 2Al2O3
In a certain experiment 4.6 grams of Al was reacted with excess oxygen and 6.8 g of product was obtained. What was the percent yield of the reaction? Answer to 4 sig-figs.

7.

Calculate the mass percent of each element in C6H8N2 to 4 sig-figs. Format your answer in the following order C; H; N. Do not subtract from 100 for you final percent.

8.

A 0.150 gram sample of a compound containing carbon, hydrogen, and oxygen yielded upon combustion 0.396 g of CO2 and 0.162 g of H2O. What is the molecular formula of the compound? The molar mass of the compound is 200.36 grams/mole. Write your formula in the following format CxHyOz

9.

Calculate the molarity of an H2C2O4 solution if 12.50 mL of it reacts with 25.72 mL of 0.09950 M NaOH.
H2C2O4(aq) + 2 NaOH(aq) —> Na2C2O4(aq) + 2 H2O(l)

10.

When 43.89 grams of a compound is vaporized at 250.°C and 760.mmHg, the gas occupies a volume of 421 milliliters. What is the molar mass of the compound? Write your answer in scientific notion.