Question

1. describe the roles of reactants and products in chemical reactions. 3. how does a chemical equation show that matter is always conserved in a chemical reaction? 4. knowing that water (h2o) forms from hydrogen (h2) and oxygen (o2), write a chemical equation for the formation of water from these two elements.

Explanation:

Step1: Define reactants and products

Reactants are substances that start a chemical reaction, and products are substances formed. In a chemical reaction, reactants are consumed to form products.

Step2: Explain conservation in chemical equations

A chemical equation is balanced to show that matter is conserved. The number of atoms of each element on the reactant side must equal the number on the product side. For the formation of water from hydrogen and oxygen, the equation is $2H_2 + O_2
ightarrow 2H_2O$. Here, we have 4 hydrogen atoms and 2 oxygen atoms on both sides.

Step3: Write the water - formation equation

The chemical equation for the formation of water from hydrogen and oxygen is $2H_2(g)+O_2(g)
ightarrow 2H_2O(l)$. The 'g' indicates gaseous state and 'l' indicates liquid state.

Answer:

1. Reactants are substances that participate in a chemical reaction and are consumed to form products. Products are the substances that are formed as a result of the chemical reaction.
2. A chemical equation shows that matter is conserved because the number of atoms of each element on the reactant side is equal to the number of atoms of the same element on the product side. For example, in the formation of water $2H_2 + O_2

ightarrow 2H_2O$, there are 4 hydrogen atoms and 2 oxygen atoms on both sides of the equation.

1. The chemical equation for the formation of water from hydrogen and oxygen is $2H_2(g)+O_2(g)

ightarrow 2H_2O(l)$.