Question

Find the balanced coefficients of the following chemical reaction:aqueous silver nitrate combines with aqueous calcium bromide to produce solid silver bromide and calcium nitratea. 1,1,1,1c. 3,1,3,1d 2,1,2,1b. 1,2,3,2

Answer 1

Step 1 - Writing the chemical equation

The first step is to identify the reactants and the products:

`\begin{gathered} \text{aqueous silver nitrate }\to AgNO_(3(aq)) \\ \text{aqueous calcium bromide }\to CaBr_(2(aq)) \\ solid\text{ silver bromide }\to AgBr_((s)) \\ \text{solid calcium nitrate }\to Ca(NO_3)_(2(s)) \end{gathered}`

The first two are the reactants, whereas the last two are the products. The reaction would be thus:

`AgNO_(3(aq))+CaBr_(2(aq))\to AgBr_((s))+Ca(NO_3)_(2(s))`

Step 2 - Balancing the reaction

To balance a chemical reaction, we must guarantee the number of atoms of the same element in each side of the equations is the same. We must guarantee this because during a chemical reaction no atom can be created nor destroyed.

Let's take a further look at the reaction in step 1:

`AgNO_(3(aq))+CaBr_(2(aq))\to AgBr_((s))+Ca(NO_3)_(2(s))`

Note, first, that there are two bromine atoms in the left-hand side, but only one bromine atom in the right-hand side. We can solve this by multiplying the substance AgBr by two:

`AgNO_(3(aq))+CaBr_(2(aq))\to2AgBr_((s))+Ca(NO_3)_(2(s))`

Now note that there are two silver (Ag) atoms in the right-hand side , but only one silver atom in the left-hand side. We can solve this by multiplying the substance AgNO3 by two:

`2AgNO_(3(aq))+CaBr_(2(aq))\to2AgBr_((s))+Ca(NO_3)_(2(s))`

Finally, let's count all atoms, just to make sure the reaction is properly balanced:

`\begin{gathered} \text{left}-\text{hand side} \\ Ag\text{ atoms }\to\text{ 2} \\ N\text{ atoms }\to\text{ 2} \\ O\text{ atoms }\to\text{ 6} \\ Ca\text{ atoms }\to\text{ 1} \\ Br\text{ atoms }\to\text{ 2} \end{gathered}`

Comparing with the other side:

`\begin{gathered} right-\text{hand side} \\ Ag\text{ atoms }\to\text{ 2} \\ N\text{ atoms }\to\text{ 2} \\ O\text{ atoms }\to\text{ 6} \\ Ca\text{ atoms }\to\text{ 1} \\ Br\text{ atoms }\to\text{ 2} \end{gathered}`

We can see the reaction is thus properly balanced.

Step 3 - Finding the coefficients

The coefficients are the bigger numbers before the substances. If there's no number, it means 1. The correct order would be then 2, 1, 2, 1. Item d) is thus the correct one.