## Introduction

Chemical names and formulas are essential to understand the properties and reactions of various compounds. However, memorizing them can be a challenge. In this article, we will provide you with six chemical names and formulas practice problems to help you master them.

## Problem 1: Water

Water is a common compound that we encounter every day. Its chemical formula is H_{2}O. This means that each water molecule contains two hydrogen atoms and one oxygen atom. What is the mass of one mole of water molecules?

### Solution:

The molar mass of water is 18.02 g/mol. Therefore, one mole of water molecules has a mass of 18.02 grams.

## Problem 2: Sodium Chloride

Sodium chloride is a compound that we commonly know as table salt. Its chemical formula is NaCl. What is the percent composition of sodium in sodium chloride?

### Solution:

The molar mass of NaCl is 58.44 g/mol. The molar mass of sodium is 22.99 g/mol. Therefore, the percent composition of sodium in NaCl is: (22.99 g/mol / 58.44 g/mol) x 100% = 39.34%

## Problem 3: Ammonia

Ammonia is a compound that is commonly used in cleaning products. Its chemical formula is NH_{3}. What is the percent composition of nitrogen in ammonia?

### Solution:

The molar mass of NH_{3} is 17.03 g/mol. The molar mass of nitrogen is 14.01 g/mol. Therefore, the percent composition of nitrogen in NH_{3} is: (14.01 g/mol / 17.03 g/mol) x 100% = 82.21%

## Problem 4: Carbon Dioxide

Carbon dioxide is a compound that is produced when we exhale. Its chemical formula is CO_{2}. What is the mass of one molecule of carbon dioxide?

### Solution:

The molar mass of CO_{2} is 44.01 g/mol. To find the mass of one molecule, we need to divide the molar mass by Avogadro’s number: 44.01 g/mol / 6.02 x 10^{23} molecules = 7.32 x 10^{-23} g/molecule

## Problem 5: Methane

Methane is a compound that is commonly used as a fuel. Its chemical formula is CH_{4}. What is the percent composition of carbon in methane?

### Solution:

The molar mass of CH_{4} is 16.04 g/mol. The molar mass of carbon is 12.01 g/mol. Therefore, the percent composition of carbon in CH_{4} is: (12.01 g/mol / 16.04 g/mol) x 100% = 74.96%

## Problem 6: Hydrochloric Acid

Hydrochloric acid is a compound that is commonly used in the production of various chemicals. Its chemical formula is HCl. What is the mass of one mole of hydrochloric acid molecules?

### Solution:

The molar mass of HCl is 36.46 g/mol. Therefore, one mole of HCl molecules has a mass of 36.46 grams.

## Conclusion

Chemical names and formulas are essential to understand the properties and reactions of various compounds. By practicing these six problems, you can improve your understanding of chemical names and formulas. Remember to always check your answers and seek help if you need it.