# Find the number of #"CO"_2# that exert a pressure of #"785 torr"# at a volume of #"32.5 L"# and a temperature #32^@"C"#?

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find the number of co2 that exert a pressure of 785torrs at a volume of 32.5L and a temperature 32c ?

find the number of co2 that exert a pressure of 785torrs at a volume of 32.5L and a temperature 32c ?

##### 1 Answer

#### Explanation:

I'm assuming that the question wants you to determine the *number of moles* of carbon dioxide,

Your tool of choice here will be the **ideal gas law** equation

#color(blue)(PV = nRT)" "# , where

*number of moles* of gas

*universal gas constant*, equal to

**absolute temperature** of the gas

Now, the problem provides you with everything that you need in order to solve for the number of moles of gas. **However**, notice that some of the units used in the expression of **do not** match those given to you.

This means that you're going to have to do a couple of **units conversions** to get your units **to match** those used in expression of

#"1 atm " = " 760 torr"#

#t ["K"] = 273.15 + t [""^@"C"]#

Rearrange the ideal gas law equation to solve for

#PV = nRT implies n = (PV)/(RT)#

Plug in your values to get

#n = (785/760color(red)(cancel(color(black)("atm"))) * 32.5color(red)(cancel(color(black)("L"))))/(0.0821(color(red)(cancel(color(black)("atm"))) * color(red)(cancel(color(black)("L"))))/("mol" * color(red)(cancel(color(black)("K")))) * (273.15 + 32)color(red)(cancel(color(black)("K")))) = "1.3399 moles"#

Rounded to two **sig figs**, the number of sig figs you have for the temperature of the gas, the answer will be

#n = color(green)("1.3 moles CO"_2)#