Question

Question #aa424

Answer 1

You rearrange the equation to isolate the missing variable and solve. You do not cross multiply.

Explanation:

Example
You are given the following information about a gas: `V_1="25 L"`; `T_1="350 K"`; `T_2="270 K"`. What is the new volume `(V_2)`?

Equation
`V_1/T_1=V_2/T_2`

Solution
Rearrange the equation to isolate `V_2`, substitute the given values, and solve.

`V_1/T_1=V_2/T_2`

Multiply both sides by `T_2` in order to isolate `V_2`.

`V_1/T_1(T_2)=V_2/cancelT_2(cancelT_2)`

`V_2=(V_1T_2)/T_1`

`V_2=((25"L")xx(270cancel"K"))/(350cancel"K")`

`V_2="19 L"`

Notice that there was no cross multiplying. Instead, both sides of the equation were multiplied times `T_2`, which cancelled it out on the `V_2` side and multiplied it times `V_1` on the other side.