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What mass, in grams, of hydrogen gas forms during the complete reaction of 10.01 g of calcium with water?

a) 1.8 g
b) 2.0 g
c) 4.4 g
d) 5.6 g

1 Answer

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Final answer:

To calculate the mass of hydrogen gas formed during the reaction of calcium with water, you need to use the balanced equation and mole ratios. The given mass of calcium is used to calculate the number of moles of calcium, which is then used to find the number of moles of hydrogen gas using the mole ratio from the equation. Finally, the moles of hydrogen gas are converted to grams using the molar mass of hydrogen.

Step-by-step explanation:

The balanced equation for the reaction of calcium (Ca) with water (H₂O) is:

Ca + 2H₂O --> Ca(OH)₂ + 2H₂

According to the equation, one mole of calcium reacts with two moles of water to produce two moles of hydrogen gas (H₂). To find the mass of hydrogen gas formed, we need to calculate the number of moles of calcium in the given mass of calcium, and then use the mole ratio from the balanced equation to find the number of moles of hydrogen gas. Finally, we can convert the moles of hydrogen gas to grams using the molar mass of hydrogen.

Step 1: Calculate the number of moles of calcium:

Moles of calcium = given mass of calcium / molar mass of calcium

Molar mass of calcium (Ca) = 40.08 g/mol

Moles of calcium = 10.01 g / 40.08 g/mol = 0.2497 mol

Step 2: Use the mole ratio from the balanced equation to find the number of moles of hydrogen gas:

Moles of hydrogen gas = 2 * moles of calcium = 2 * 0.2497 mol = 0.4994 mol

Step 3: Convert the moles of hydrogen gas to grams using the molar mass of hydrogen:

Molar mass of hydrogen (H₂) = 2.02 g/mol

Mass of hydrogen gas = moles of hydrogen gas * molar mass of hydrogen

Mass of hydrogen gas = 0.4994 mol * 2.02 g/mol = 1.01 g

Therefore, the mass of hydrogen gas formed during the complete reaction of 10.01 g of calcium with water is 1.01 g.

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