- 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.
- 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.