Question

При нагревании кальций-гидрид разлагается с образованием металла и водорода. Водород, полученный в результате разложения кальций-гидрида массой 7,0 г., пропустили над раскалённым вольфрам(VI)-оксидом массой 4,0 г. Определите массу полученного вольфрама.

Answer 1

CaH2=Ca+H2
n(CaH2)=7:42=0.2 моль=n(H2)
M(CaH2)=42
WO3+3H2=W+3H2O
n(WO3)=4:232=0.02 моль=n(W)
M(WO3)=232
1 WO3-----3H2
0.02---------x  x=0.06 моль надо H2, а есть 0.2 мольH2- в избытке, решаем по недостатку по WO3
m(W)=184*0.02=3.68 г

Answer 2

Decomposition of Calcium Hydride and Reaction with Tungsten(VI) Oxide

When calcium hydride (CaH2) is heated, it decomposes to form calcium metal (Ca) and hydrogen gas (H2). In this case, hydrogen gas with a mass of 7.0 g is reacted with heated tungsten(VI) oxide (WO3) with a mass of 4.0 g. We need to determine the mass of tungsten (W) obtained from this reaction.

To solve this problem, we can use the concept of stoichiometry and the balanced chemical equation for the reaction between hydrogen gas and tungsten(VI) oxide.

The balanced chemical equation for the reaction is as follows:

2H2 + WO3 -> 2H2O + W

From the balanced equation, we can see that 2 moles of hydrogen gas react with 1 mole of tungsten(VI) oxide to produce 1 mole of water and 1 mole of tungsten.

To find the mass of tungsten obtained, we need to calculate the number of moles of hydrogen gas and then use the mole ratio to determine the number of moles of tungsten. Finally, we can convert the moles of tungsten to grams using its molar mass.

Calculation:

1. Calculate the number of moles of hydrogen gas: - Given mass of hydrogen gas =