Education.com
Try
Brainzy
Try
Plus

# Chemistry and Chemical Equations for Nursing School Entrance Exam Study Guide (page 2)

By
Updated on Aug 12, 2011

Practice questions for this study guide can be found at:

Chemistry and Chemical Equations for Nursing School Entrance Exam Practice Problems

### Chemical Equations and Stoichiometry

1. Molecular Weight
2. Molecular weight is the sum of the atomic weights of all the atoms in a molecular formula. It is the same as the molar mass (in grams) without the unit.

3. Moles
4. A mole of a particular substance is equal to the number of as many atoms as there are atoms in exactly 12 g of the carbon-12 atom. Experiments established that number to be 6.02214199 × 1023 particles (Avogadro's number).

5. Chemical Equations
1. Balancing Equations
2. The method of balancing equations is called "trial and error."

• Write the correct formulas for all reactants and products.
• Compare the number of atoms on the reactant and product(s) sides.
• Rebalance and recheck if necessary.
• Always balance the heavier atoms before trying to balance lighter ones, such as H.
• Use fractions if necessary to reduce coefficients or use the smallest possible whole number.
• Verify (again!) that the number of atoms of each element is balanced.
3. Use of Moles in Chemical Equations
4. Stoichiometry establishes the quantities of reactants used and products obtained based on a balanced chemical equation.

6. Percentage Yield
7. Percentage yield is a ratio of the actual yield of a product over the expected one, called a theoretical yield.

8. Basic Types of Chemical Reactions
• Combination reactions:
• A + B → C

H2 + O2 → H2O

• Decomposition reactions:
• C → A + B

CaCO3 → CaO + CO2

• Single displacement reactions:
• A + BC → B + AC

Zn + 2HCl → H2 + ZnCl2

• Double displacement reactions:
• AB + CD → AC + BD

HCl + NaOH → H2O + NaCl

### You Should Review

• balancing equations and using polyatomic ions in balancing equations

Practice questions for this study guide can be found at:

Chemistry and Chemical Equations for Nursing School Entrance Exam Practice Problems