Question

Assuming the gas obeys the ideal gas law, use the value of the slope ‘m’ to find the number of moles. The slope calculated is related to the Universal Gas Constant, R, with the following equation: m = nRT.

For a fixed n and V, which quantity will increase the pressure if you increase it? 

          

    b)  For a fixed N and T, which quantity will increase the pressure if you decrease it? 

         

    c)  For a fixed V and T, which quantity will decrease the pressure if you decrease it? 

          

Answer 1

$(a)$ By using the ideal gas equation,

$PV=nRT =m$ (According to the question)

If $n$ and $V$ are constant , it means Pressure $(P)$ will be a dependent variable on Temperature $(T).$

And $P\propto T$

So, if we increase the temperature of ideal gas, pressure will also increase at a constant $n$ and $V.$

$(b)$ If $n$ and $T$ are constant ,which means $m=nRT$ is constant.

So, $PV=m$ where $m$ is constant.

or , $P\propto \frac{1}{V}$

Hence ,if we decrease the volume of the gas $(V)$ ,pressure will increase at constant $n$ and $T.$

$(c)$ By using the ideal gas equation,

$PV=nRT =m$ (According to the question)

If $V$ and $T$ are constant , it means Pressure $(P)$ will be a dependent variable on number of moles $(n).$

And $P\propto n$

So, if we decrease the number of moles of ideal gas, pressure will also decrease at a constant $T$ and $V.$