Combustion Analysis and Concentration (Worksheet)

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Work in groups on these problems. You should try to answer the questions without referring to your textbook. If you get stuck, try asking another group for help.

Q1.

Combustion analysis of toluene a common organic solvent, gives 5.86 mg of $$CO_2$$ and 1.37 mg of $$H_2O$$. If the compound only contains carbon and hydrogen, what is its empirical formula?

2. Menthol is composed of C, H, and O. A 0.1005 g sample is combusted, producing 0.2829 g of $$CO_2$$ and 0.1159 g of $$H_2O$$. What is the empirical formula for menthol? If the compound has a molar mass of 156 g/mol, what is its molecular formula?

3. Combustion of 2.78 mg of ethyl butyrate produces 6.32 mg of $$CO_2$$ and 2.58 mg of $$H_2O$$. What is the empirical formula is the compound is composed of C, H, and O?

Q4. Calculate

1. the number of grams of solute in 0.250 L of 0.150 M $$KBr$$
2. Molar concentration of a solution containing 4.75 g of $$Ca(NO_3)_2$$ in 0.200L
3. the volume of 1.50 M $$Na_3PO_4$$ in milliliters that contains 5.00 g of solute.

Q5.

a. How many milliliter of a stock solution of 10.0 M $$HNO_3$$ would you have to use to prepare 0.350 L of 0.400 M $$HNO_3$$?

b. If you dilute 25.0 mL of the stock solution to a final volume of 0.500 L what will be the concentration of the diluted solution?

Q6.

What mass of $$NaCl$$ is needed to precipitate the silver ions from 20.0 mL of 0.100 M $$AgNO_3$$ solution?

$NaCl_{(aq)} + AgNO_{3\; (aq)} \rightarrow NaNO_{3\;(aq)} + AgCl_{(s)}$

7. How many milliters of 0.120 M $$HCl$$ are needed to completely neutralize 50.0 mL of 0.101 M $$Ba(OH)_2$$ solution?

$2HCl + Ba(OH)_2 \rightarrow BaCl_2 + 2H_2O$