To determine the number of moles of hydrochloric acid (HCl) required to react with sodium thiosulfate (Na2S2O3) of 0.66 molarity, we first need to understand the reaction that occurs.
The balanced chemical reaction between hydrochloric acid and sodium thiosulfate is:
\[ \text{Na}_2\text{S}_2\text{O}_3 + 2 \text{HCl} \rightarrow \text{2 NaCl} + \text{H}_2\text{O} + \text{SO}_2 \]
From this reaction, we can see that 1 mole of sodium thiosulfate reacts with 2 moles of hydrochloric acid.
Step 1: Determine the volume of sodium thiosulfate
To calculate the number of moles of hydrochloric acid required, we first need the number of moles of sodium thiosulfate involved in the reaction. The volume (in liters) of the sodium thiosulfate solution must be known. However, since you provided only the molarity (0.66 M) but not the volume, we cannot determine the moles unless a specific volume is given.
Step 2: Calculate moles of Na2S2O3
If you have a specific volume \( V \) (in liters) of the sodium thiosulfate solution, you can calculate the moles of sodium thiosulfate using the formula:
\[ \text{Moles of } \text{Na}_2\text{S}_2\text{O}_3 = \text{Molarity} \times \text{Volume} \]
Step 3: Find moles of HCl required
Once you have the moles of sodium thiosulfate, use the stoichiometry from the balanced equation to find the moles of hydrochloric acid:
\[ \text{Moles of HCl} = 2 \times \text{Moles of Na}_2\text{S}_2\text{O}_3 \]
Example Calculation
For example, if you have 1 liter of sodium thiosulfate solution:
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Moles of Na2S2O3: \[ \text{Moles of Na}_2\text{S}_2\text{O}_3 = 0.66 , \text{mol/L} \times 1 , \text{L} = 0.66 , \text{moles} \]
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Moles of HCl required: \[ \text{Moles of HCl} = 2 \times 0.66 = 1.32 , \text{moles} \]
If you provide the volume of the sodium thiosulfate solution, I can assist you further with calculating the exact number of moles of hydrochloric acid required.