General Knowledge
In which part of a chemical reaction do limiting and excess reagents appear?
The start / left/ beginning / reactants.
What is an excess reagent?
Reactants that are not used up when the reaction is finished
What is a limiting reagent?
The reagent that is completely used up or reacted.
Mg(OH)2+2HCl→MgCl2+2H2O
How many grams of MgCl2 will be produced from 16.0 of Mg(OH)2 and 11.0g of GCI?
14.4 grams of MgCl2
What is the first step that needs to be completed in order to find the limiting reagent in a chemical reaction?
Balance the equation.
What happens when there isn't enough of one reactant in a chemical reaction?
The reaction stops abruptly.
True or false: Chemical reactions with exact stoichiometric amounts of reactants have no limiting or excess reagents.
True
What is one way of finding the limiting reagent?
By calculating the amount of product that can be formed by each reactant.
NaCl+AgNO3→AgCl+NaNO3
How many grams of AgCl will be produced from 5.00g of NaCl and 103 g of AgNO3?
12.3 grams of AgCl
Zn+CuCl2→ZnCl2+Cu
How many grams of ZnCl2 will be produced from 7.00g of Zn and 8.00 g of CuCl2?
What needs to happen to figure out the amount of product produced?
We must determine which reactant will limit the chemical reaction and which reactant is in excess.
If 4.5 moles of sodium reacts with 3.4 moles of chlorine gas to product salt, which is the excess reagent?
2Na + Cl2 --> 2NaCl
Cl2
if 4.95 g of ethylene (C2H4) are combusted with 3.25 g of oxygen.
a)What is the limiting reagent?
b)How many grams of CO2 are formed?
a)O2
b)2.98 g CO2
Zn+CuCl2→ZnCl2+Cu
How many grams of ZnCl will be produced from 32.0 of Zn and 13.0 of CuCl2?
13.2 grams of ZnCl2
For the reaction
2S(s)+30 2(g) ---> 2SO3(g)
If 6.3 g of S is reacted with 10.0g of O2 show by calculating which one will be the limiting reactant.
9.43g O2
Chemical reaction equations give the ideal stoichiometric relationship among ______ and ______.
reactants, products
Take the reaction: NH3 + O2 --> NO + H2O. In an experiment, 3.25 g of NH3 are allowed to react with 3.50 g of O2.
How much of the excess reactant remains after the reaction?
1.76 g NH3 left
How many grams of Al2S3 are formed when 5.00grams of Al is heated with 10.0 grams S?
13.9g Al2S3
CH4+2O2→CO2+2H2O
How many grams of CO2 will be produced from 12.0g of CH4 and 133 g of O2?
32.9 grams of CO2
Which element is in excess when 3.00 grams of Mg is ignited in 2.20 grams of pure oxygen?
What mass is in excess ? What mass of Mg is formed?
0.23g O2
Why are excess and limiting reagents important?
They let us know when the reaction cannot proceed and limits it from continuing.
Cu+2AgNO3→2Ag+Cu(NO3)2
How many grams of Ag will be produced from 5.00 Cu and 1 .00 of AgNO3?
0.635 grams of Ag
When MoO3 and Zn are heated together they react
3 Zn(s)+2 MoO3 ---> MoO3(s)+ZnO(s)
What mass of ZnO is formed when 20.0 grams of MoO3 is reacted with 10.0 grams of Zn?
12.4 g ZnO
Mg(OH)2+2HCl→MgCl2+2H2O
How many grams of MgCl2 will be produced from 16.0 of Mg(OH)2 and 11.0 g of HCI?
14.4 grams of MgCl2
Zinc and sulphur react to form zinc sulphide according to the equation
Zn+S ---> ZnS
If 25.0 g of zinc and 30.0 g os=f sulphur are mixed,
a)Which chemical is the limiting reactant?
b)How many grams of ZnS will be formed?
c)How many grams of the excess reactant will remain after the reaction is over?
a) Zn = LR
b)37.3 g ZnS
c)12.3g S