I think that the answer could be A. X and Y
Answer:
Q = -897 kJ/mol
Explanation:
From the given information:
The heat released Q = -65.9 kJ
To start with the molar mass of
= 2 × (molar mass of H) + 2 × (molar mass of O)
= (2 × 1.008) + (2 × 16.0 )
= 34.016 g/mol
However, given that:
mass of
2.50 g
The number of moles of
= 


Finally; Using the formula:

Q = -897 kJ/mol
Answer:
75.47
Explanation:
AS WE CANT WEIGHT AIR THE ANSWER IS CORRECT
Answer:
Molar mass of the unknown gas: 146 g /mol
Explanation:
At STP, any "ideal" gas is contained in a volume of 22.4L. This situation, for 1 mol of gas. In this case we have:
0.5 g / 4 g/mol = 0.125 moles of He
These amount of He occupies 0.125 mol . 22.4L / 1 mol = 2.8 L so the double of volume will be occupied by the unkown gas.
22.4 L / 1 mol = (2.8 L . 2) / x moles
22.4L / 1 mol = 5.6 L / x mol
x mol = 5.6L / 22.4L → 0.25 moles
To determine the molar mass of the unknown gas → 36.5 g / 0.25 mol = 146 g /mol