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Stoichiometry Using Balanced Equations: How to Go From Grams/Moles of A to Grams/Moles of B

Coefficients in a balanced chemical equations represent molar ratios. For example if we have 2A+ 3B -->C, this means that 2 moles of A need to react with 3 moles of B to produce 1 mol of C.

Therefore, we can use balanced equations to go from moles of one substance to moles of another using coefficients.

In this guide, we will learn how to go from moles of A to moles of B, grams of A to moles of B, and grams of A to grams of B.



The chart below shows three different pathways.

  1. To go from moles of A to moles of B, we need to use the coefficients in the balanced equation.

  2. To go from grams of A to moles of B, we must first convert grams of A to moles of A using molar mass of A from the Periodic Table, and then use the coefficients to go from moles of A to moles of B.

  3. To go from grams of A to grams of B, we must first convert grams of A to moles of A using molar mass of A from the Periodic Table. Then use the coefficients to go from moles of A to moles of B. Finally, convert moles of B to grams of B using Molar Mass of B (Molar mass is found by using the Periodic Table). Examples are shown below.



Stoichiometry Using Balanced Equations
Stoichiometry Using Balanced Equations

Converting moles of A to moles of B using a balanced equation

Converting moles of A to moles of B using a balanced equation
Converting moles of A to moles of B using a balanced equation

The question is asking to find moles of B if 14 moles of A are given. We always start with the number given. In this case 14 moles of A. We then put moles of A at the bottom to cancel and moles of B on top. According to the balanced equation there are 2 moles of A for every 1 mol of B.


Converting grams of A to moles of B using a balanced equation

Determine how many moles of water are produced in the oxidation of 1.00 g of glucose?
Determine how many moles of water are produced in the oxidation of 1.00 g of glucose?

We start with one gram of glucose and use molar mass (180 grams per mole) to go from grams to moles. We then convert moles of glucose to moles of water by using the coefficients in the balanced equation. There are 6 moles of water produced for every 1 mol of glucose reacted.


Converting grams of A to grams of B using a balanced equation

Determine how many grams of water are produced in the oxidation of 1.00 g of glucose?
Determine how many grams of water are produced in the oxidation of 1.00 g of glucose?

We start with one gram of glucose and use molar mass (180 grams per mole) to go from grams to moles. We then convert moles of glucose to moles of water by using the coefficients in the balanced equation. There are 6 moles of water produced for every 1 mol of glucose reacted. Finally, we convert moles of water to grams of water by using molar mass of water (18 grams per 1 mol).


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