At STP, 72 grams of HCL react with 3.5 grams of magnesium. What volume of Hydrogen will be produced? What is the limiting reactant? What is the reactant in excess?
Would anyone know how to do this, I really want to know how to do these kind of problems, and my teacher really doesn't explain good.
Would anyone know how to do this, I really want to know how to do these kind of problems, and my teacher really doesn't explain good.
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S/he doesn't explain well, you mean? Or her/his explanations are not good.
Chemicals are made up of atoms. All chemistry is about these little particles' reactions. When they react to form a specific compound they ALWAYS react in the same number ratios.
If Calcium reacts with Chlorine to form Calcium chloride the ratio of Calcium to Chlorine to Calcium Chloride is ALWAYS the same. It is 1:2:1. Always. IF 31 Calciums react, then we know that 62 Chlorine atoms react and that those 93 atoms will form 31 formula equivalents of Calcium Chloride.
If 1.5 moles of Chlorine (atomic) reacts with Calcium, (reacts completely), we KNOW that 0.75 moles of Calcium reacted. Always the same number ratio.
When solving a chemical reaction question, you should always figure out what the formula (equation) is. Why? Because the equation tells you the number ratios of the reactants and products and so you can figure out weights, volumes, yields, etc. from it.
First step: Write down the equation (assuming that it is not what you are trying to figure out).
HCl + Mg → MgCl + H is the first part of figuring out the equation
but H is not the stable form of hydrogen at stp, H2 is. And Mg "always" ionizes to +2 and Cl "always" ionizes to -1 (almost always). So MgCl is +2-1 = +1 not neutral and must be wrong. MgCl is not the formula for Magnesium Chloride. MgCl2 is... +2 -2*(-1)= 0.
So we know the products are MgCl2 and H2 and we know the reactants are HCl and Mg
We are now ready to figure out what the ratios are
HCl + Mg → H2 + MgCl2 I see that I need at least 2 H's and 2 Cl's on the left so I will try this
Chemicals are made up of atoms. All chemistry is about these little particles' reactions. When they react to form a specific compound they ALWAYS react in the same number ratios.
If Calcium reacts with Chlorine to form Calcium chloride the ratio of Calcium to Chlorine to Calcium Chloride is ALWAYS the same. It is 1:2:1. Always. IF 31 Calciums react, then we know that 62 Chlorine atoms react and that those 93 atoms will form 31 formula equivalents of Calcium Chloride.
If 1.5 moles of Chlorine (atomic) reacts with Calcium, (reacts completely), we KNOW that 0.75 moles of Calcium reacted. Always the same number ratio.
When solving a chemical reaction question, you should always figure out what the formula (equation) is. Why? Because the equation tells you the number ratios of the reactants and products and so you can figure out weights, volumes, yields, etc. from it.
First step: Write down the equation (assuming that it is not what you are trying to figure out).
HCl + Mg → MgCl + H is the first part of figuring out the equation
but H is not the stable form of hydrogen at stp, H2 is. And Mg "always" ionizes to +2 and Cl "always" ionizes to -1 (almost always). So MgCl is +2-1 = +1 not neutral and must be wrong. MgCl is not the formula for Magnesium Chloride. MgCl2 is... +2 -2*(-1)= 0.
So we know the products are MgCl2 and H2 and we know the reactants are HCl and Mg
We are now ready to figure out what the ratios are
HCl + Mg → H2 + MgCl2 I see that I need at least 2 H's and 2 Cl's on the left so I will try this
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