Learning Stoich! By Emily Harris

Using Hydrochloric acid plus Calcium hydroxide as an example

Balancing equations

The balanced equation for this example is 2HCl+Ca(OH)2---> CaCl2+2H2O

This is the most important part of Stoich, it is the base of all the work we are about to do.

IUPAC names?

Hydrogen Hydroxide + Calcium Chloride

IUPAC is just a fancy way for asking what the names of the reactants and Products are.

Molar Mass

Molar mass is the mass of an element that equals one mole. It is found right under the elements symbol on the PT. The molar mass for this equation is as follows:

2HCl+Ca(OH)2---->CaCl2+2H2O

37.469_74.092----->80.156_36.03

Mole to Mole conversions??

Mole to mole conversions isn't to hard, it's taking a certain weight of one object and finding how much of another object you have. The problem will give you a certain amount of moles and what it wants you to find. So we go back to the equation we wrote earlier, and use that to convert from one thing to another. Example: You have 11.3 Moles of HCl and i want Ca(OH)2. So we find both of those compounds in the equation and use the number in front of it. We enter it into something called 'trAintracks' 11.3 m would go in first and then below it in the next column you would put 2 HCl to cancel out the HCl so we can get to Ca(OH)2. then we put 2 m HCL. Then we multiply across and divide and we get 5.65 m Ca(OH)2
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Limiting and excess reactant

The limiting reactant is the reason that the reaction stopped, there was not enough of one reactant to have another reaction. The excess reactant is the opposite of that, where there was to much left over but couldn't do anything because there was not enough of the limiting reactant.

Theoretical yield

The theoretical yield is the calculation of how much you should end up with if everything went perfectly, this never happens but the end result should come very close. To find it you just have to divide the actual yield by the percent yield and multiply by 100.
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Percent yield

The percentage yield is the ratio between the actual yield and the theoretical yield multiplied by 100%. The actual yelled is what you actually got from the reaction.
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But what does it mean??

The two substances react with each other forming the salt calcium chloride and water. It is a double replacement so two elements switch places to create something new. In this case it makes salt and water.