when a quantity of powdered sulphur is burnt in excess oxygen, 100cm3 of SO2 were produced at STP

CAL,the vol of gas at STD

What's STD?

To determine the volume of the gas at standard temperature and pressure (STP), we first need to calculate the number of moles of sulfur dioxide (SO2) produced.

We can use the ideal gas law to do this, which states:

PV = nRT

Where:
P is the pressure of the gas
V is the volume of the gas
n is the number of moles
R is the ideal gas constant (0.0821 L.atm/mol.K)
T is the temperature in Kelvin

At STP, the pressure is 1 atmosphere (atm) and the temperature is 273 Kelvin (K).

Given that 100 cm3 of SO2 were produced, we need to convert this volume to liters:

1 cm3 = 0.001 L

So, the volume of SO2 produced is:
100 cm3 * 0.001 L/cm3 = 0.1 L

Now, we can rearrange the ideal gas law equation to solve for the number of moles (n):

n = PV / RT

n = (1 atm * 0.1 L) / (0.0821 L.atm/mol.K * 273 K)
n = 0.000436 moles

Now that we have the number of moles of SO2, we can calculate the volume of the gas at standard temperature and pressure (STD). STP has a temperature of 0 °C (273 Kelvin) and a pressure of 1 atmosphere.

Again, we can use the ideal gas law equation, rearranged to solve for volume:

V = nRT / P

V = (0.000436 mol * 0.0821 L.atm/mol.K * 273 K) / 1 atm
V = 0.00936 L

Therefore, the volume of the gas at STD is 0.00936 liters.