由理想气体状态方程:
PV=nRT;
n=m/M;
又∵密度ρ=质量/体积=m/V [kg/(m^3)];T为温度(开尔文温标K=273+℃);
R为一常数,约为8.31447焦耳/(mole K);1焦耳=kg m^2/ s^2
M为气体分子量( 0.001 kg/mole),氮气为28.02,氧气32,二氧化碳44.01;
∴压强P[10^-5bar]=(RT/M)ρ; 1Pascal=1kg/(m s^2)= 10^-5 bar
或
ρ=PM/RT=(10^-5)* pM/RT, 压强p单位=bar---------------------------------(1)
从(1)算某种气体压强与密度的数据
举例来说
温度是25℃=273+25=298K
P=2bar,M=32*0.001(氧气kg/mole),R=8.31447焦耳/(mole K)=8.31447(kg m^2/ s^2)/(mole K)
氧气密度ρ=(10^-5)* pM/RT=2.583*(10^-10)*kg/(m^3)
参考资料:http://www.lenntech.com/calculators/molecular/molecular-weight-calculator.htm