Answer : The pressure of the gas using both the ideal gas law and the van der Waals equation is, 60.2 atm and 44.6 atm respectively.
Explanation :
First we have to calculate the pressure of gas by using ideal gas equation.

where,
P = Pressure of
gas = ?
V = Volume of
gas = 0.805 L
n = number of moles
= 1.93 mole
R = Gas constant = 
T = Temperature of
gas = 306 K
Now put all the given values in above equation, we get:


Now we have to calculate the pressure of gas by using van der Waals equation.

P = Pressure of
gas = ?
V = Volume of
gas = 0.805 L
n = number of moles
= 1.93 mole
R = Gas constant = 
T = Temperature of
gas = 306 K
a = pressure constant = 
b = volume constant = 
Now put all the given values in above equation, we get:
![(P+\frac{(4.19L^2atm/mol^2)\times (1.93mole)^2}{(0.805L)^2})[0.805L-(1.93mole)\times (5.11\times 10^{-2}L/mol)]=1.93mole\times (0.0821L.atm/mol.K)\times 306K](https://tex.z-dn.net/?f=%28P%2B%5Cfrac%7B%284.19L%5E2atm%2Fmol%5E2%29%5Ctimes%20%281.93mole%29%5E2%7D%7B%280.805L%29%5E2%7D%29%5B0.805L-%281.93mole%29%5Ctimes%20%285.11%5Ctimes%2010%5E%7B-2%7DL%2Fmol%29%5D%3D1.93mole%5Ctimes%20%280.0821L.atm%2Fmol.K%29%5Ctimes%20306K)

Therefore, the pressure of the gas using both the ideal gas law and the van der Waals equation is, 60.2 atm and 44.6 atm respectively.
Answer: 36.6°C
Explanation:
Given that,
initial pressure of helium (P1) = 1.20 atm
Initial temperature (T1) = 22.0°C
Final temperature (T2) = ?
Final pressure of helium (P2) = 2.00 atm
Since pressure and temperature are given while volume is constant, apply the formula for pressure's law
P1/T1= P2/T2
1.20 atm / 22.0°C = 2.00 atm / T2
Cross multiply
1.20 atm•T2= 2.00 atm•22°C
1.20 atm•T2= 44 atm•°C
Divide both sides by 1.20 atm
1.20 atm•T2/1.20 atm = 44 atm•°C/1.20 atm
T2 = 36.6°C
Chromium and copper (ii) sulfate react according the reaction below;
2Cr + 3CuSO4 = 3Cu +Cr2(SO4)3
We can calculate the number of moles of CuSO4 present;
no of moles of CuSO4 = 0.75 × 0.125 = 0.09735 moles
According to the reaction the mole ratio is 2 : 3
Moles of Chromium = (0.09735 × 2)/3
= 0.0625 Moles
Mass of chromium = 0.0625 moles × 52 g/mole
= 3.25 g of chromium