Question

student study guide - chemical reactions & acids/bases
part 1: chemical reactions and balancing

1. a chemical reaction is a process in which substances change to form new _.
2. the law of conservation of mass states that matter cannot be _ or _.
3. to show this in an equation, the number of each type of atom on the _ must equal the number on the _.
4. the large numbers placed in front of chemical formulas are called _.
5. a chemical equation is balanced when both sides have the same number of each type of _.
6. you can only change the _ (never the subscripts) when balancing an equation.
7. example: _ h₂ + _ o₂ → _ h₂o
8. indications that a chemical reaction has occurred are _, _, _, _ (exothermic), _ (endothermic), and _.

Explanation:

Step1: Recall chemical reaction basics

A chemical reaction forms new substances.

Step2: Remember Law of Conservation of Mass

Matter can't be created or destroyed.

Step3: Understand equation balancing

Front numbers (coefficients) make atom counts equal on reactant and product sides.

Step4: Define large numbers

Large numbers (coefficients) are called coefficients.

Step5: Check chemical equation balance

Same atom type counts mean balance.

Step6: Know balancing rule

Only change coefficients (not subscripts).

Step7: Balance example equation

$$2H_2 + O_2 ightarrow 2H_2O$$

Step8: List reaction indications

Indications: gas production, precipitate formation, color change, temperature change (exothermic or endothermic), light emission.

Answer:

1. substances
2. created; destroyed
3. reactant; product
4. coefficients
5. atom
6. coefficients
7. \(2\); \(1\); \(2\)
8. gas production; precipitate formation; color change; temperature change; light emission