Sodium thiosulfate (Na₂S₂O₃)the major component in photographic fixer solution, reacts with silver bromide to dissolve it according to the following reaction:AgBr(s)+2 Na₂S₂O₃ (aq) → Na₃Ag(S₂O₃)₂(aq)+ NaBr(aq)b. How many mL of 0.02 M Na₂S₂O₃ contain this number of moles?

Verified step by step guidance

1. Identify the number of moles of Na₂S₂O₃ needed from the balanced chemical equation. Note that 2 moles of Na₂S₂O₃ react with 1 mole of AgBr.
2. Use the molarity formula: Molarity (M) = moles of solute / liters of solution, to find the volume of Na₂S₂O₃ solution needed.
3. Rearrange the formula to solve for the volume of the solution: Volume (L) = moles of solute / Molarity (M).
4. Substitute the given molarity (0.02 M) and the number of moles of Na₂S₂O₃ into the equation.
5. Convert the volume from liters to milliliters by multiplying by 1000, since 1 L = 1000 mL.

Key Concepts

Molarity

Molarity (M) is a measure of concentration defined as the number of moles of solute per liter of solution. It is crucial for understanding how to calculate the amount of a substance in a given volume of solution. In this question, the molarity of sodium thiosulfate (Na₂S₂O₃) is given as 0.02 M, which indicates that there are 0.02 moles of Na₂S₂O₃ in every liter of solution.

Stoichiometry

Stoichiometry is the area of chemistry that deals with the relationships between the quantities of reactants and products in a chemical reaction. In the provided reaction, the stoichiometric coefficients indicate the molar ratios of the reactants and products, which are essential for determining how many moles of Na₂S₂O₃ are needed to react with a given amount of silver bromide (AgBr).

Volume Calculation

Volume calculation involves determining the volume of a solution required to achieve a specific number of moles based on its molarity. To find the volume in milliliters (mL) of the 0.02 M Na₂S₂O₃ solution that contains a certain number of moles, the formula used is: Volume (L) = Moles / Molarity. This calculation is essential for practical applications in laboratory settings.