Question

Determine the number of moles of the compound and determine the number of moles of each type of atom in 2.12 g of potassium bromide, KBr.

Answer 1

To find the number of moles of potassium bromide (KBr) in a 2.12 g sample, calculate the molar mass of KBr (119 g/mol) and divide the mass of the sample by the molar mass. The result is approximately 0.0178 moles of KBr, which also corresponds to 0.0178 moles of potassium atoms and 0.0178 moles of bromine atoms due to the 1:1 ratio of elements in the compound.

Step-by-step explanation:

To determine the number of moles of potassium bromide (KBr) in 2.12 g of the compound, we first need to calculate its molar mass. The molar mass of K (potassium) is approximately 39.10 g/mol, and the molar mass of Br (bromine) is approximately 79.90 g/mol. Therefore, the molar mass of KBr is the sum of the molar masses of K and Br, which is 39.10 g/mol + 79.90 g/mol = 119 g/mol.

Next, we use the formula:

Number of moles = mass in grams / molar mass

In this case, the calculation for KBr is:

Number of moles = 2.12 g / 119 g/mol ≈ 0.0178 moles

To determine the number of moles of each type of atom, we recognize that in one mole of KBr, there is one mole of K atoms and one mole of Br atoms. Since we have calculated the number of moles of KBr to be approximately 0.0178, this also represents the number of moles of K and Br in the sample, because there's a 1:1 ratio of potassium to bromine atoms in KBr.

Therefore, the sample contains approximately 0.0178 moles of potassium atoms and 0.0178 moles of bromine atoms.

Answer 2

The number of moles of KBr is 0.0178 moles

The number of moles of K is 0.0178 moles

The number of moles of Br is 0.0178 moles

EXPLANATION

Given that;

The mass of the compound is 2.12 grams

The name of the compound is KBr

Follow the steps below to find the number of moles of the compound

Step 1; Apply the mole formula

`\text{ mole = }\frac{\text{ mass}}{\text{ molar mass}}`

The molar mass of KBr is 119.002 g/mol

`\begin{gathered} \text{ mole = }\frac{\text{ 2.12}}{\text{ 119.002}} \\ \text{ mole = 0.0178 moles} \end{gathered}`

The number of moles of KBr is 0.0178 moles

Part B

`\text{ KBr }\rightarrow\text{ K}^+\text{ + Br}^-`

In the above reaction, 1 mole of KBr is equivalent to 1 mole of K and 1 mole of Br

Recall, the Avogadro's number is 6.022 x 10^23

`\begin{gathered} \text{ For K atom} \\ \text{ 1 mole of potassium in KBr = 1 }*\text{ number of moles of KBr} \\ \text{ Mole of potassium = 1 }*\text{ 0.0178} \\ \text{ Mole of potassium = 0.0178 moles} \end{gathered}`
`\begin{gathered} \text{ For Br} \\ \text{ mole of Br = 1 }*\text{ mole of KBr} \\ \text{ Mole of Br = 1 }*\text{ 0.0178} \\ \text{ Mole of Br = 0.0178 mole} \end{gathered}`