70cm3 of hydrogen are sparked with 25cm3 of oxygen at s.t.p the total volume of residual gas after cooling is ?
First, we need to use the balanced chemical equation to determine the volume ratio of reactants to products:
2H2 + O2 -> 2H2O
This means that for every 2 volumes of hydrogen, we need 1 volume of oxygen to react and produce 2 volumes of water vapor.
In this case, we have 70cm3 of hydrogen and 25cm3 of oxygen. To determine which reactant is limiting, we need to compare the volume ratio with the actual ratio:
Hydrogen: 70cm3 / 2 = 35
Oxygen: 25cm3 / 1 = 25
Since we have less oxygen than required by the volume ratio, it is the limiting reactant. This means that all 25cm3 of oxygen will be consumed, and we can calculate the volume of water vapor produced:
2H2 + O2 -> 2H2O
1 volume of oxygen produces 2 volumes of water vapor, so 25cm3 of oxygen will produce 50cm3 of water vapor.
Next, we need to determine the total volume of residual gas after cooling. Since water vapor is a gas at room temperature and pressure, we can assume that it will remain in the gas phase. Therefore, the total volume of residual gas will be the sum of the unreacted hydrogen and the water vapor:
Residual gas = 70cm3 - 35cm3 (used in reaction) + 50cm3 (water vapor) = 85cm3
Therefore, the total volume of residual gas after cooling is 85cm3.
To find the total volume of residual gas after cooling, we need to calculate the total volume of the gases present before the reaction and then subtract the volume of gases that reacted.
First, let's calculate the total volume of gases before the reaction:
Total Volume of Hydrogen = 70 cm^3
Total Volume of Oxygen = 25 cm^3
Now, let's calculate the volume of gases that reacted:
Hydrogen reacts with Oxygen in a 2:1 ratio. So, for every 2 cm^3 of Hydrogen, 1 cm^3 of Oxygen reacts.
Let's check how much Oxygen will react:
Oxygen initially present = 25 cm^3
Oxygen required for the reaction = 2/1 * Hydrogen (70 cm^3)
Oxygen required for the reaction = 2/1 * 70 cm^3 = 140 cm^3
Since we only have 25 cm^3 of Oxygen, all of the Oxygen will react, leaving a deficit of 140 cm^3 - 25 cm^3 = 115 cm^3 of Hydrogen unreacted.
This means that 115 cm^3 of Hydrogen is the residual gas after the reaction.
Therefore, the total volume of residual gas after cooling is 115 cm^3.