If we use the reaction Sulphuric Acid with Sodium Hydroxide. The reaction equation is
H2SO4 + 2NaOH = Na2SO4 + 2H2O
Note the molar ratios are 1:2::1:2
However if we have say 75 grams sulphuric acid. what masses are required by sodium hydroxide to make the reaction go to completion. Also what masses of sodium sulphate and water will produce.
First we calculate the moles of H2SO4 . To do this we find the atomic masses.
H x 2 = 1 x 2 = 2
S x 1 = 32 x 1 = 32
O x 4 = 16 x 4 = 64
2 + 32 + 64 = 98
So moles(H2SO4) = 75 / 98 = 0.7653moles ( equivalent to one(1) ratio).
Hence moles (NaOH) = 0.7653 x 2 = 1.5306 ( equivalent to two(2) ratios)
Hence masses of NaOH required for complete reaction is
mass(g) = 1.5306 x (23 + 16 + 1) = 61.44 g.
So total mass of reactants is 75 + 61.44 = 136.44. g
As per the Law of conservation of Mass , the total mass of the products will be 136.44 g. This figure has to be apportioined for the product masses.
Since there are two moles of water produced , then mass of water is
Mass(H2O) =1.5306 x 18) = 27.5508 g
Hence mass of sodium sulphate is 136.44 - 27.5508n = 108.892 g
To verfiy this
First calculate the Relative Molecular mass of Na2SO4
which is
Na x 2 = 23 x 2 = 46
S x 1 = 32 x 1 = 32
O x 4 = 16 x 4 = 64
46 + 32 + 64 = 142
Mass(Na2SO4) = 0.7653 x 142 = 108.67 g ~ 108.892g
The difference in these figures is due to estimations, and calculator errors.
Hopefully you can see ,what stoichiometry is all about. !!!!!
the coefficients give the ratio of moles reactant to moles product
Stoichiometry relates moles of reactant to moles of product, so if you have the amount of reactant in the equation, you can calculate the amount of product produced.
The coefficients give the ratio of moles reactant to moles product.
A reactant that gives the lowest yield by limiting the amount of product is called a limiting reactant. The limiting reactant will run out, so that only a limited amount of product can be made from the reactants.
Using an excess of another reactant limits a reactant.
In a chemical reaction the limiting reactant is the reactant that there is the least of in the reaction; it determines the amount of product formed. In a chemical reaction it is the reactant that gets completely "used up"
Stoichiometry relates moles of reactant to moles of product, so if you have the amount of reactant in the equation, you can calculate the amount of product produced.
The coefficients give the ratio of moles reactant to moles product.
A reactant that gives the lowest yield by limiting the amount of product is called a limiting reactant. The limiting reactant will run out, so that only a limited amount of product can be made from the reactants.
The limiting reactant is that reactant in a chemical reaction that will be used up first. Put another way, it is the reactant that is in the smallest supply. The way it controls the amount of product formed is that once it is used up, no more product can be formed, so the amount of product formed ultimately depends on the amount of the limiting reactant.
Using an excess of another reactant limits a reactant.
When the limiting reactant is completely used up. A limiting reactant is the reactant that determines the amount of product. To determine this use the balanced chemical reaction with the masses of the reactants to determine the moles of product formed. The reactant that forms the least amount of product will be the limiting reactant.
If you know how many you have put in, you know how many you should get out (in theory; yield is often nowhere near the perfect result).
In a chemical reaction the limiting reactant is the reactant that there is the least of in the reaction; it determines the amount of product formed. In a chemical reaction it is the reactant that gets completely "used up"
The amount of product is determined by the limiting reactant. Once one reactant is used completely, no more product can be produced.
The more reactant, the faster the reaction The less reactant, the slower the reaction hope that clears it up for you
because the limiting reactant is not in excess so it's all used up . as the limiting reactant is used up the reaction stops so no more product can be made.
determines the amount of product that will form