Question

при восстановлении оксида вольфрама(4) водородом масса тв.остатка оказалась на 12г меньше массы исход. образца, а массовая доля оксида в конечной смеси стала равна 20%. Вычислить исх.массу оксида, взятую для восстановления.

Answer 1

WO2+2H2=W+2H2O

n(H2O)=12:18=0,666; n(WO2)=0,666:2=0,333; m(WO2)=0,333x216-72;

ответ:72грамма...................................................................................

Answer 2

Calculation of the Initial Mass of Tungsten Oxide

To calculate the initial mass of tungsten oxide (WO3) taken for reduction, we can use the given information. According to the problem statement, when tungsten oxide (WO3) is reduced by hydrogen (H2), the mass of the solid residue is 12 grams less than the mass of the initial sample. Additionally, the mass fraction of the tungsten oxide in the final mixture is 20%.

Let's denote the initial mass of the tungsten oxide as M.

From the given information, we can set up the following equations:

Equation 1: Mass of the solid residue = M - 12 grams Equation 2: Mass fraction of tungsten oxide in the final mixture = 20%

To solve for the initial mass of tungsten oxide, we need to find the value of M.

Solution:

From Equation 1, we have:

Mass of the solid residue = M - 12 grams

From Equation 2, we have:

Mass fraction of tungsten oxide in the final mixture = 20%

To find the initial mass of tungsten oxide, we can set up the following equation:

(M - 12 grams) / (M - 12 grams + mass of hydrogen) = 0.20

Simplifying the equation, we get:

(M - 12 grams) / (M - 12 grams + mass of hydrogen) = 1/5

Cross-multiplying, we have:

5(M - 12 grams) = M - 12 grams + mass of hydrogen

Expanding and simplifying, we get:

5M - 60 grams = M - 12 grams + mass of hydrogen

4M = 48 grams + mass of hydrogen

M = (48 grams + mass of hydrogen) / 4

Therefore, the initial mass of tungsten oxide taken for reduction is (48 grams + mass of hydrogen) / 4.

Please note that the mass of hydrogen is not provided in the given information, so we cannot calculate the exact value of the initial mass of tungsten oxide without that information.