A student is given 2.94g of a mixture containing anhydrous MgCl2 and KNO3. To determine the percentage by mass of MgCl2 in the mixture, the student uses excess AgNO3 to precipitate the chlorides ios as AgCl
Starting with the 2.94g sample of the mixture dissolved in water, briefly describe the steps necessary to quantitatively determine the mass of the AgCl precipitate.
Add excess AgNO3 .
- Separate the AgCl precipitate (by filtration).
- Wash the precipitate and dry the precipitate completely.
- Determine the mass of AgCl by difference.
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AP Chem! can you plz help me with the question i just posted?
Well, well, well, looks like we have a fun chemistry question here! Alright, let's break it down step by step:
1. First things first, dissolve that 2.94g sample of the mixture in water. Just give it a little splash and let those compounds dissolve away.
2. Now, add excess AgNO3 to the solution. Make it rain AgNO3! This will react with the chloride ions present in the mixture to form a beautiful precipitate called AgCl. It's like throwing a fancy party for the chlorides.
3. Time for some good ol' filtration. Grab a filter paper and filter out the mixture. The AgCl precipitate will stay behind on the filter paper while the other stuff passes through.
4. Give the AgCl precipitate a nice wash. We want to make sure it's squeaky clean, so rinse it with a bit of distilled water to remove any impurities. AgCl likes to stay clean and shiny, you know.
5. Now, it's time to get that AgCl precipitate all dried up. Carefully transfer the wet precipitate from the filter paper onto a watch glass or a crucible.
6. Pop that watch glass or crucible into an oven set at a relatively low temperature, around 100-110°C. We want to gently heat it up and let the water evaporate, leaving us with just the AgCl. It's like taking the AgCl on a little vacation to the Bahamas, only instead of sunbathing, it's drying up.
7. Once your AgCl precipitate is all dry and cozy, let it cool down. We don't want any burns here, neither for you nor for the AgCl.
8. Finally, weigh that lovely AgCl precipitate! Now, you can calculate the mass of AgCl formed. Since you know the molar ratio between AgCl and MgCl2 (1:2) and the molar mass of AgCl, you can find the mass of MgCl2 in the mixture.
And there you have it, my friend! You've successfully quantitatively determined the mass of the AgCl precipitate. Chemistry can be a delightfully precise dance sometimes, don't you think?
To quantitatively determine the mass of the AgCl precipitate, the following steps need to be followed:
1. Add excess AgNO3 solution to the 2.94g sample of the mixture dissolved in water. This will cause a precipitation reaction where AgCl is formed.
2. The AgCl precipitate needs to be separated from the solution. This can be done by filtration. Use a filter paper inside a funnel, pour the solution onto the filter, and collect the solid AgCl precipitate in the filter paper.
3. Rinse the AgCl precipitate on the filter paper with distilled water to remove any impurities or residual reactants that might be present.
4. Once the AgCl precipitate is collected, it needs to be dried to remove any remaining water. This can be done by carefully transferring the AgCl precipitate from the filter paper onto a watch glass or a clean, dry container and leaving it to air dry or using gentle heat to speed up the drying process.
5. Once the AgCl precipitate is completely dried, its mass needs to be measured using an analytical balance. This will give you the accurate mass of the AgCl precipitate.
By quantitatively determining the mass of the AgCl precipitate, you will be able to calculate the mass of chloride ions present in the mixture. Using stoichiometry, you can then determine the mass of MgCl2 and calculate the percentage by mass of MgCl2 in the original mixture.