Question

Смесь кальция и оксида кальция массой 5 г обработали водой. В результате реакции выделилось 1,68 л газа (н. у.). Определите массовую долю оксида кальция в исходной смеси.

Answer 1

Если что w-это амега
Ca + 2H2O→ Ca(OH)2 +H2 
CaO + H2O→Ca(OH)2 
1)n(H2)= V/Vm= 1.68 /22.4= 0.075  моль 
 2)n(H2)=n(Ca)=0,075 моль 
3)m(Ca)=0.075*40= 3г 
4)w(Ca)=m(Ca)/m(смеси)=3/(5)*100%=60% 
5)w(CaO)=100%-w(Ca)=100%-60%=40%

Answer 2

Calculation of the Mass Fraction of Calcium Oxide

To determine the mass fraction of calcium oxide in the initial mixture, we need to use the information provided about the reaction and the volume of gas produced.

Given: - Mass of the mixture (calcium + calcium oxide) = 5 g - Volume of gas produced (at standard temperature and pressure) = 1.68 L

To calculate the mass fraction of calcium oxide, we can use the ideal gas law and the molar volume of an ideal gas at standard temperature and pressure (STP), which is 22.4 L/mol.

The balanced chemical equation for the reaction between calcium and water is not provided, so we cannot directly calculate the molar ratio between calcium oxide and the gas produced. However, we can still determine the mass fraction of calcium oxide using the given information.

Since the volume of gas produced is given at STP, we can assume that the reaction goes to completion and that the molar volume of the gas is directly proportional to the moles of gas produced.

To calculate the moles of gas produced, we can use the molar volume of an ideal gas at STP:

Moles of gas = Volume of gas (at STP) / Molar volume of gas at STP

Moles of gas = 1.68 L / 22.4 L/mol

Moles of gas = 0.075 mol

Since the moles of gas produced are directly proportional to the moles of calcium oxide, we can assume that the moles of calcium oxide are also 0.075 mol.

To calculate the mass of calcium oxide, we need to know the molar mass of calcium oxide. However, the molar mass of calcium oxide is not provided, so we cannot directly calculate the mass of calcium oxide.

Therefore, without the molar mass of calcium oxide, we cannot determine the mass fraction of calcium oxide in the initial mixture.

Please provide the molar mass of calcium oxide so that we can calculate the mass fraction accurately.