Determine the mass of zinc sulphide,ZnS which is produced when 6.2 g of zinc and 4.5 g of sulphur are reacted.
To determine the mass of zinc sulphide (ZnS) produced when 6.2 g of zinc (Zn) and 4.5 g of sulphur (S) are reacted, we need to calculate the molar ratio between Zn and ZnS, as well as the molar ratio between S and ZnS.
The molar ratio between Zn and ZnS can be determined from the chemical equation of the reaction:
Zn + S → ZnS
From the equation, we can see that 1 mole of zinc (Zn) reacts with 1 mole of sulphur (S) to produce 1 mole of zinc sulphide (ZnS). Therefore, the molar ratio between Zn and ZnS is 1:1.
Next, we need to convert the masses of zinc and sulphur into moles using their respective molar masses.
The molar mass of Zn is approximately 65.38 g/mol.
The molar mass of S is approximately 32.07 g/mol.
To find the number of moles of Zn and S, we can use the following formulas:
Number of moles = mass / molar mass
Number of moles of Zn = 6.2 g / 65.38 g/mol
Number of moles of Zn = 0.095 moles
Number of moles of S = 4.5 g / 32.07 g/mol
Number of moles of S = 0.140 moles
Now that we have the number of moles of Zn and S, we can determine the limiting reactant. The limiting reactant is the reactant that is completely consumed and determines the amount of product formed. We compare the mole ratios to determine which reactant is in excess.
Since the molar ratio between Zn and ZnS is 1:1, and the number of moles of Zn is 0.095 moles, we can conclude that 0.095 moles of ZnS will be produced.
Similarly, the molar ratio between S and ZnS is 1:1, and the number of moles of S is 0.140 moles. Therefore, 0.140 moles of ZnS will also be produced.
Since both reactants are in excess, we choose the reactant that produces the lowest number of moles, which is 0.095 moles of ZnS.
Finally, to calculate the mass of ZnS produced, we multiply the number of moles of ZnS by its molar mass:
Mass of ZnS = number of moles of ZnS * molar mass of ZnS
The molar mass of ZnS is the sum of the molar masses of Zn and S:
Molar mass of ZnS = 65.38 g/mol + 32.07 g/mol
Molar mass of ZnS = 97.45 g/mol
Mass of ZnS = 0.095 moles * 97.45 g/mol
Mass of ZnS = 9.27 g
Therefore, the mass of zinc sulphide (ZnS) produced when 6.2 g of zinc and 4.5 g of sulphur are reacted is 9.27 g.