Question
When the alkaline earth metal strontium reacts with water, it forms strontium hydroxide and hydrogen gas. Use what you've learned about molar masses and mole ratios to complete the following.
strontium+ water → strontium hydroxide + hydrogen
Sr (s) + 2H2O (l) → Sr(OH)2 (aq) +H2 (g)
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)
g/mol Sr(OH)2
Moles Water
strontium+ water → strontium hydroxide + hydrogen
Sr (s) + 2H2O (l) → Sr(OH)2 (aq) +H2 (g)
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)
g/mol Sr(OH)2
Moles Water
Answers
GPT-4o mini
To solve your problem, let's break it down step by step.
### Step 1: Calculate the molar mass of Sr(OH)₂
The molar mass of Sr(OH)₂ can be calculated by adding up the molar masses of its constituent atoms:
- Strontium (Sr): 87.62 g/mol
- Oxygen (O): 16.00 g/mol (and there are 2 oxygen atoms in Sr(OH)₂)
- Hydrogen (H): 1.01 g/mol (and there are 2 hydrogen atoms in Sr(OH)₂)
#### Calculation:
\[ \text{Molar mass of Sr(OH)}_2 = \text{Molar mass of Sr} + 2 \times \text{Molar mass of O} + 2 \times \text{Molar mass of H} \]
\[ \text{Molar mass of Sr(OH)}_2 = 87.62 \, \text{g/mol} + 2 \times 16.00 \, \text{g/mol} + 2 \times 1.01 \, \text{g/mol} \]
\[ \text{Molar mass of Sr(OH)}_2 = 87.62 \, \text{g/mol} + 32.00 \, \text{g/mol} + 2.02 \, \text{g/mol} \]
\[ \text{Molar mass of Sr(OH)}_2 = 121.64 \, \text{g/mol} \]
So, the molar mass of Sr(OH)₂ is **121.64 g/mol**.
### Step 2: Determine how many moles of water are needed to form 5 moles of Sr(OH)₂
From the balanced chemical equation:
\[ \text{Sr (s)} + 2\text{H}_2\text{O (l)} \rightarrow \text{Sr(OH)}_2 \text{ (aq)} + \text{H}_2 \text{ (g)} \]
We can see that 1 mole of Sr(OH)₂ requires 2 moles of water (H₂O).
Thus, to determine how many moles of water are needed to form 5 moles of Sr(OH)₂, we can set up the following proportion:
\[ \text{Moles of water} = 5 \text{ moles of Sr(OH)}_2 \times 2 \text{ moles of H}_2\text{O per mole of Sr(OH)}_2 \]
\[ \text{Moles of water} = 5 \times 2 = 10 \text{ moles of H}_2\text{O} \]
Therefore, you would need **10 moles of water** to form 5 moles of Sr(OH)₂.
### Summary:
1. Molar mass of Sr(OH)₂ = **121.64 g/mol**
2. Moles of water needed for 5 moles of Sr(OH)₂ = **10 moles**.
### Step 1: Calculate the molar mass of Sr(OH)₂
The molar mass of Sr(OH)₂ can be calculated by adding up the molar masses of its constituent atoms:
- Strontium (Sr): 87.62 g/mol
- Oxygen (O): 16.00 g/mol (and there are 2 oxygen atoms in Sr(OH)₂)
- Hydrogen (H): 1.01 g/mol (and there are 2 hydrogen atoms in Sr(OH)₂)
#### Calculation:
\[ \text{Molar mass of Sr(OH)}_2 = \text{Molar mass of Sr} + 2 \times \text{Molar mass of O} + 2 \times \text{Molar mass of H} \]
\[ \text{Molar mass of Sr(OH)}_2 = 87.62 \, \text{g/mol} + 2 \times 16.00 \, \text{g/mol} + 2 \times 1.01 \, \text{g/mol} \]
\[ \text{Molar mass of Sr(OH)}_2 = 87.62 \, \text{g/mol} + 32.00 \, \text{g/mol} + 2.02 \, \text{g/mol} \]
\[ \text{Molar mass of Sr(OH)}_2 = 121.64 \, \text{g/mol} \]
So, the molar mass of Sr(OH)₂ is **121.64 g/mol**.
### Step 2: Determine how many moles of water are needed to form 5 moles of Sr(OH)₂
From the balanced chemical equation:
\[ \text{Sr (s)} + 2\text{H}_2\text{O (l)} \rightarrow \text{Sr(OH)}_2 \text{ (aq)} + \text{H}_2 \text{ (g)} \]
We can see that 1 mole of Sr(OH)₂ requires 2 moles of water (H₂O).
Thus, to determine how many moles of water are needed to form 5 moles of Sr(OH)₂, we can set up the following proportion:
\[ \text{Moles of water} = 5 \text{ moles of Sr(OH)}_2 \times 2 \text{ moles of H}_2\text{O per mole of Sr(OH)}_2 \]
\[ \text{Moles of water} = 5 \times 2 = 10 \text{ moles of H}_2\text{O} \]
Therefore, you would need **10 moles of water** to form 5 moles of Sr(OH)₂.
### Summary:
1. Molar mass of Sr(OH)₂ = **121.64 g/mol**
2. Moles of water needed for 5 moles of Sr(OH)₂ = **10 moles**.