Question

1. Calculate the molar mass of Sr(OH)2 to the nearest hundredth or two decimals. Interactive Periodic Table Link 2. Determine how many moles of water would be needed to form 5 moles of Sr(OH)2 (2 points) 121.64 g/mol Sr(OH)2 Moles Water

Answer 1

1. To calculate the molar mass of strontium hydroxide, Sr(OH)2, we need to add the molar masses of its constituent elements: strontium (Sr), oxygen (O), and hydrogen (H).

- Molar mass of Strontium (Sr) = 87.62 g/mol
- Molar mass of Oxygen (O) = 16.00 g/mol
- Molar mass of Hydrogen (H) = 1.01 g/mol

The formula for strontium hydroxide, Sr(OH)2, contains:
- 1 strontium atom
- 2 oxygen atoms
- 2 hydrogen atoms

Now, we can calculate the molar mass:
\[
\text{Molar mass of Sr(OH)2} = (1 \times 87.62 \, \text{g/mol}) + (2 \times 16.00 \, \text{g/mol}) + (2 \times 1.01 \, \text{g/mol})
\]

Calculating it step-by-step:
- Molar mass of Sr = \( 87.62 \, \text{g/mol} \)
- Molar mass of 2 O = \( 2 \times 16.00 = 32.00 \, \text{g/mol} \)
- Molar mass of 2 H = \( 2 \times 1.01 = 2.02 \, \text{g/mol} \)

Adding those together:
\[
87.62 + 32.00 + 2.02 = 121.64 \, \text{g/mol}
\]

So, the molar mass of Sr(OH)2 is **121.64 g/mol**.

2. To determine how many moles of water (H2O) are needed to form 5 moles of Sr(OH)2, we need to look at the balanced chemical reaction for the formation of strontium hydroxide. The formation of Sr(OH)2 from Sr and H2O can be written as:
\[
\text{Sr} + 2 \text{H2O} \rightarrow \text{Sr(OH)2} + \text{H2}
\]

From the balanced equation, we can see that 2 moles of water are needed to produce 1 mole of Sr(OH)2. Therefore, to calculate the amount of water needed for 5 moles of Sr(OH)2, we can use the following ratio:
\[
\text{Moles of H2O} = 5 \, \text{moles Sr(OH)2} \times \frac{2 \, \text{moles H2O}}{1 \, \text{mole Sr(OH)2}} = 10 \, \text{moles H2O}
\]

Thus, **10 moles of water are needed to form 5 moles of Sr(OH)2**.