To solve this problem, we can start by looking at the stoichiometry of the equation:
\[ 2H_2O \rightarrow 2H_2 + O_2 \]
This means that 2 moles of water (H₂O) produce 2 moles of hydrogen (H₂) and 1 mole of oxygen (O₂).
From the given data:
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The molar mass of hydrogen (H₂) is approximately 2 g/mol. Therefore, 112 g of hydrogen corresponds to: \[ \text{Moles of } H_2 = \frac{112 \text{ g}}{2 \text{ g/mol}} = 56 \text{ mol} \]
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The molar mass of oxygen (O₂) is approximately 32 g/mol. Therefore, 888 g of oxygen corresponds to: \[ \text{Moles of } O_2 = \frac{888 \text{ g}}{32 \text{ g/mol}} = 27.75 \text{ mol} \]
According to the balanced equation, the ratio of moles of H₂ to O₂ produced is 2:1. If we have 56 moles of H₂, the molar requirement for O₂ would be: \[ \text{Moles of } O_2 = \frac{56 \text{ mol H}_2}{2} = 28 \text{ mol O}_2 \]
However, we calculated only 27.75 moles of O₂ were collected, which indicates a slight discrepancy.
Now we can determine the mass of water that produced this hydrogen and oxygen. The reaction indicates for every 2 moles of H₂O, we produce 2 moles of H₂ and 1 mole of O₂.
Given that 56 moles of H₂ produces: \[ \text{Moles of } H_2O = 56 \text{ mol H}_2 = 56 \text{ mol H}_2O \quad (\text{2:2 ratio}) \] This means: \[ \text{Mass of } H_2O = 56 \text{ mol} \times 18 \text{ g/mol} = 1008 \text{ g} \]
Based on this analysis, the initial mass of water (approximately 1008 g) was indeed very close to 1000 g, but since the calculation suggests a slight excess of water due to rounding, it's reasonable to round down to 1000 g.
Thus, the correct answer ultimately seems to be that:
Neither are correct. It was approximately 1000g.
So, in conclusion:
- Student A is incorrect because, while the water wasn’t measured, the initial conditions can still be deduced from the products.
- Student B is also somewhat incorrect, as the precise deduction would indicate slightly more than 1000g based on calculations.
The closest reasonable interpretation is that one might argue that the water initially was very near to 1000 g based on rounding considerations in practical terms. However, a precise calculation would suggest around 1008 g.