Question

A sample of air has a volume of 157.9 mL at 116°C. At what temperature (in 'C) will its volume be 62.7 mlif the pressure is held constant?-119-96.0139182

Answer 1

1) List the known and unknown quantities.

Sample: air.

Pressure: constant

Volume 1: 157.9 mL.

Temperature 1: 116 ºC.

Volume 2: 62.7 mL

Temperature 2: unknown.

2) Convert units

2.1- Convert mL to L

`L=157.9\text{ }mL*\frac{1\text{ }L}{1000\text{ }mL}=0.1579\text{ }L`
`L=62.7\text{ }mL*\frac{1\text{ }L}{1000\text{ }mL}=0.0627\text{ }L`

2.2- Convert ºC to K

`K=116\text{ }ºC+273.15=389.15\text{ }K`

3) Set the equation.

`(V1)/(T1)=(V2)/(T2)`

4) Plug in the known quantities and solve for T2.

`T2=\frac{(0.0627\text{ }L)(389.15\text{ }K)}{0.1579\text{ }L}`
`T2=154.52\text{ }K`

5) Convert K to ºC.

`ºC=K-273.15`
`ºC=154.52\text{ }K-273.15=-118.63\text{ }ºC`

The temperature is -119 ºC.

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