A solution contains Cr³⁺ ions and Mg²⁺ ions. The addition of 1.00 L of 1.51 M NaF solution causes the complete precipitation of these ions as CrF₃(s) and MgF₂(s). The total mass of the precipitate is 49.6 g. Find the mass of Cr³⁺ in the original solution.

검증된 단계별 안내

Determine the moles of NaF added using the concentration and volume: \( \text{moles of NaF} = 1.51 \text{ M} \times 1.00 \text{ L} \).

Write the balanced chemical equations for the precipitation reactions: \( \text{Cr}^{3+} + 3\text{F}^- \rightarrow \text{CrF}_3(s) \) and \( \text{Mg}^{2+} + 2\text{F}^- \rightarrow \text{MgF}_2(s) \).

Calculate the moles of \( \text{CrF}_3 \) and \( \text{MgF}_2 \) that can be formed using the stoichiometry of the reactions and the moles of NaF available.

Use the molar masses of \( \text{CrF}_3 \) and \( \text{MgF}_2 \) to express the total mass of the precipitate in terms of the moles of \( \text{CrF}_3 \) and \( \text{MgF}_2 \).

Set up an equation for the total mass of the precipitate (49.6 g) and solve for the moles of \( \text{CrF}_3 \), then calculate the mass of \( \text{Cr}^{3+} \) in the original solution.

비슷한 문제에 대한 검증된 영상 답변:

이 영상 해법은 위 문제에 도움이 된다고 튜터들이 추천한 것입니다.

영상 길이:

10m

주요 개념

질문에 올바르게 답하기 위해 반드시 이해해야 하는 핵심 개념들은 다음과 같습니다.

Stoichiometry

Stoichiometry is the calculation of reactants and products in chemical reactions. It involves using balanced chemical equations to determine the relationships between the amounts of substances consumed and produced. In this question, stoichiometry is essential for relating the moles of Cr3+ and Mg2+ ions to the moles of their respective precipitates, CrF3 and MgF2.

Precipitation Reactions

Precipitation reactions occur when two soluble salts react in solution to form an insoluble solid, known as a precipitate. In this case, the addition of NaF leads to the formation of CrF3 and MgF2 precipitates. Understanding the solubility rules and the conditions under which these ions precipitate is crucial for determining the mass of the original ions in the solution.

Molar Mass

Molar mass is the mass of one mole of a substance, typically expressed in grams per mole (g/mol). It is used to convert between the mass of a substance and the number of moles. In this problem, calculating the mass of Cr3+ requires knowing its molar mass to relate the total mass of the precipitate to the moles of Cr3+ that contributed to the formation of CrF3.

A solution contains Cr3+ ions and Mg2+ ions. The addition of 1.00 L of 1.51 M NaF solution causes the complete precipitation of these ions as CrF3(s) and MgF2(s). The total mass of the precipitate is 49.6 g. Find the mass of Cr3+ in the original solution.