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There are four tubes contains NaOH, Ba(NO3)2, MgSO4, ZnSO4. but they are unlabled. so we don't know which tube contains which chemical. we have to indicate each chemical. we can't use heat or other chemicals. how to do this. no ph indictors. write it step by step
Accepted Answer
Here's how you can identify the unlabeled tubes containing NaOH, Ba(NO3)2, MgSO4, and ZnSO4 using only visual observation and simple tests:
1. Observation: Look for any visible precipitates. If you see a white, cloudy precipitate, it likely indicates the presence of BaSO4, formed from the reaction of Ba(NO3)2 and MgSO4 or ZnSO4.
2. Confirmation: Take a small sample from the suspected BaSO4 precipitate tube and add a drop of NaOH solution. If the precipitate dissolves, it confirms the presence of BaSO4 (as it reacts with NaOH to form soluble Ba(OH)2 and Na2SO4). If the precipitate does not dissolve, it indicates ZnSO4 or MgSO4 is present.
3. Identifying MgSO4 or ZnSO4: Take a sample from the remaining unlabeled tube that likely contains either MgSO4 or ZnSO4. Add a small amount of NaOH to it. If a white precipitate forms, it's Mg(OH)2, indicating the presence of MgSO4. If no precipitate forms, it's ZnSO4, as Zn(OH)2 is soluble in excess NaOH.
4. Final Confirmation: The remaining unlabeled tube contains NaOH. You can confirm this by testing its pH with a litmus paper (if allowed). However, since you mentioned not using pH indicators, you can visually distinguish NaOH as it's often a clear, colorless solution in a high concentration.
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