If someone could show me step by step, it would be greatly appreciated!
A 20-mg strip of Magnesium metal reacts in 5.0 mL of 4.0 M HCl over a given time period. Evaluate the mol Mg / mol HCl ratio for the reaction.
A 20-mg strip of Magnesium metal reacts in 5.0 mL of 4.0 M HCl over a given time period. Evaluate the mol Mg / mol HCl ratio for the reaction.
-
Calculate moles Mg: 20 g(1 mole)/(24.31 g) = 0.823 mole Mg
Calculate moles HCl: moles = molarity HCl x volume HCl in L = (4.0 mol/L)(0.0050 L) = 0.020 mol HCl
Ratio moles Mg to moles HCl = (0.823 mol Mg)/(0.020 mol HCl) = 41.1/1 or 41 to 1
In other words, you have about 41 times as many moles of Mg as you have moles HCl. Since moles is directly related to numbers of molecules then there are 41 times as many Mg atoms as there are HCl molecules. This should tell you that there is a large excess of Mg in the reaction.
Reaction: Mg(s) + 2 HCl(aq) --> MgCl2(aq) + H2(g)
If you wanted to completely react all of the Mg metal then you would need a minimum of 2(0.823 moles of HCl) for the reaction to go to completion.
Hope this is helpful to you. JIL HIR
Calculate moles HCl: moles = molarity HCl x volume HCl in L = (4.0 mol/L)(0.0050 L) = 0.020 mol HCl
Ratio moles Mg to moles HCl = (0.823 mol Mg)/(0.020 mol HCl) = 41.1/1 or 41 to 1
In other words, you have about 41 times as many moles of Mg as you have moles HCl. Since moles is directly related to numbers of molecules then there are 41 times as many Mg atoms as there are HCl molecules. This should tell you that there is a large excess of Mg in the reaction.
Reaction: Mg(s) + 2 HCl(aq) --> MgCl2(aq) + H2(g)
If you wanted to completely react all of the Mg metal then you would need a minimum of 2(0.823 moles of HCl) for the reaction to go to completion.
Hope this is helpful to you. JIL HIR