16. If 8 grams of hydrogen gas and 64 grams of oxygen gas are formed, then how many grams of water must have been used? (You can use a calculator if needed.)
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1 point
8 grams
16 grams
64 grams
72 grams
To answer this question, we need to use the balanced chemical equation for the formation of water:
2H2 + O2 -> 2H2O
From this equation, we can see that 2 moles of hydrogen gas is needed to react with 1 mole of oxygen gas to produce 2 moles of water.
The molar mass of hydrogen is 1 g/mol and the molar mass of oxygen is 16 g/mol.
To find the number of moles of hydrogen gas in 8 grams, we divide the mass by the molar mass:
moles of H2 = 8 g / 2 g/mol = 4 moles
Since the reaction requires 2 moles of hydrogen gas for every 1 mole of oxygen gas, we need 2 moles of oxygen gas to react with the 4 moles of hydrogen gas:
moles of O2 = 2 moles
Now we can find the mass of oxygen gas using its molar mass:
mass of O2 = moles of O2 * molar mass of O2 = 2 mol * 32 g/mol = 64 grams
Therefore, 64 grams of oxygen gas must have been used.
wrong
I apologize, there was an error in my previous response. Let's try solving the problem again:
We know that 8 grams of hydrogen gas (H2) and 64 grams of oxygen gas (O2) are formed.
To calculate how many grams of water (H2O) must have been used, we need to recognize that the mass of the reactants must equal the mass of the products in a chemical reaction.
The equation for the formation of water is:
2H2 + O2 -> 2H2O
To find the mass of water used, we can subtract the mass of hydrogen and oxygen gas formed from the total mass of water formed:
Mass of water used = Mass of water formed - (Mass of hydrogen gas formed + Mass of oxygen gas formed)
Since the molar mass of hydrogen is 1 g/mol and the molar mass of oxygen is 16 g/mol, we can calculate the molar mass of water (H2O):
Molar mass of water (H2O) = (2 * molar mass of hydrogen) + molar mass of oxygen
= (2 * 1 g/mol) + 16 g/mol
= 2 g/mol + 16 g/mol
= 18 g/mol
Now, let's calculate the number of moles of hydrogen gas formed:
Moles of hydrogen gas formed = Mass of hydrogen gas formed / molar mass of hydrogen
= 8 g / 2 g/mol
= 4 mol
Similarly, let's calculate the number of moles of oxygen gas formed:
Moles of oxygen gas formed = Mass of oxygen gas formed / molar mass of oxygen
= 64 g / 32 g/mol
= 2 mol
Finally, we can calculate the mass of water used:
Mass of water used = (2 * moles of water formed) - (moles of hydrogen gas formed * molar mass of water) - (moles of oxygen gas formed * molar mass of water)
= (2 * 4 mol) - (4 mol * 18 g/mol) - (2 mol * 18 g/mol)
= 8 mol - 72 g - 36 g
= 8 mol - 108 g
= -100 g
Based on this calculation, it appears that there is a discrepancy. The mass of water used is -100 grams, which does not make sense in this context. It seems there may be an error in the given information or calculation.