A chemist uses hot hydrogen gas to convert chromium(III) oxide to pure chromium. How many grams of hydrogen are needed to <

Question

A chemist uses hot hydrogen gas to convert chromium(III) oxide to

pure chromium. How many grams of hydrogen are needed to

convert 76 grams of chromium(III) oxide, Cr203?

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Doris 5 months 2021-08-15T15:54:00+00:00 1 Answers 33 views 0

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    2021-08-15T15:55:19+00:00

    Answer: 3.024 g grams of hydrogen are needed to  convert 76 grams of chromium(III) oxide, Cr_{2}O_{3}

    Explanation:

    The reaction equation for given reaction is as follows.

    Cr_{2}O_{3} + 3H_{2} \rightarrow 2Cr + 3H_{2}O

    Here, 1 mole of Cr_{2}O_{3} reacts with 3 moles of H_{2}.

    As mass of chromium (III) oxide is given as 76 g and molar mass of chromium (III) oxide (Cr_{2}O_{3}) is 152 g/mol.

    Number of moles is the mass of substance divided by its molar mass. So, moles of Cr_{2}O_{3} is calculated as follows.

    No. of moles = \frac{mass}{molar mass}\\= \frac{76 g}{152 g/mol}\\= 0.5 mol

    Now, moles of H_{2}.given by 0.5 mol of Cr_{2}O_{3} is calculated as follows.

    0.5 mol Cr_{2}O_{3} \times \frac{3 mol H_{2}}{1 mol Cr_{2}O_{3}}\\= 1.5 mol H_{2}

    As molar mass of H_{2} is 2.016 g/mol. Therefore, mass of H_{2} is calculated as follows.

    No. of moles = \frac{mass}{molar mass}\\1.5 mol = \frac{mass}{2.016 g/mol}\\mass = 3.024 g

    Thus, we can conclude that 3.024 g grams of hydrogen are needed to  convert 76 grams of chromium(III) oxide, Cr_{2}O_{3}.

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