If the pressure, volume, and the number of moles of a gas are known, which is needed to calculate the universal gas constant from the ideal gas law?
the temperature of the gas
the molar volume of the gas
the molar mass of the gas
the partial pressure of the gas

 the temperature of the gas

Explanation: The ideal gas law has arrived from the combination of four laws:

1) Boyle's Law: This law states that pressure is inversely proportional to the volume of the gas at constant temperature and number of moles.

    (At constant temperature and number of moles)

2) Charles' Law: This law states that volume is directly proportional to the temperature of the gas at constant pressure and number of moles.

   (At constant pressure and number of moles)

3) Gay-Lussac's Law: This law states that pressure is directly proportional to the temperature of the gas at constant volume and number of moles.

    (At constant volume and number of moles)

4) Avogadro's Law: This law states that volume is directly proportional to the number of moles of the gas at constant pressure and temperature.

  (At constant temperature and pressure)

According to ideal gas law,

where,

P = pressure of the gas

V = volume of the gas

T = temperature of the gas

n = number of moles of gas

R = Gas constant

Thus to calculate the gas constant we need to know the temperature of gas.

"you start with 15.67 g mgco3-xh2o, when heated and all the water is removed, you are left with 7.58 g mgco3 only.

therefore, you had 15.67 - 7.58 = 8.09g h2o  

moles of each :

7.58g mgco3 = ? moles = 7.58g / 83.4g/mole = 0.09moles  

8 09g h2o = ? moles = 8.09g / 18g/mole = 0.44moles  

molar ratio between the two by dividing both numbers by the smallest number :

0.09 / 0.09 = 1  

0.44 / 0.09 = 4.8  

mgco3-5h2o"