Writing Chemical Equations

water freezes to form ice

sugar dissolves in water

gasoline burns in a car engine

a piece of metal expands when it is heated

When two substances react, the temperature of the mixture decreases.

When two substances react, the temperature of the mixture increases.

There is less energy going into the reactant to break the bond than there is energy leaving the product.

There is more energy going into the reactant to break the bond than there is energy leaving the product.

The amount of energy entering and leaving is the same.

(g)

(s)

(l)

Matter cannot be created.

Matter cannot be destroyed.

Matter can only be rearranged/conserved.

Matter doesn't matter.

(l)

(g)

(aq)

(s)

Manganese plus oxygen . . . .

Molybdenum plus oxygen . . . .

Magnesium plus oxygen . . . .

Heat plus oxygen

H₂ + S → HS

H₂ + S → H₂S

H + S→ HS

H + S→ H₂S

$$CO_{2_{\ }}+\ H_2O\ \rightarrow\ CH_4\ +H_2\$$

$$CO_2\ \rightarrow\ H_2\ +\ CH_4\ +\ H_2O$$

$$CO_2\ \ +\ H_2\ +\ CH_4\ \ \rightarrow\ H_2O$$

$$CO_2\ \ +\ H_2\ \rightarrow\ CH_4\ +\ H_2O$$

$$H\ +\ CO_2\ \rightarrow\ H_2CO_3$$

$$H\ \rightarrow\ CO_2\ +\ H_2CO_{3_{ }}$$

$$H_2\ +\ CO_2\ \rightarrow\ H_2CO_3$$

$$H_2\ \rightarrow\ CO_2\ +\ H_2CO_3$$