ok, the question is this; Gemma bought some So White brand washing powder and noticed on the packet that it claimed to contain a maximum of 6.5g of P per wash. The recommended amount per wash is 3/4 cup, which weighs 100g. She decided to test the manufacturer's claim. On investigation, she found that the P is present as phosphate ions. She decided to precipitate out these phosphate ions by reacting the washing powder with magnesium sulphate (epsom salts MgSO4.7H20) and ammonia solution (NH4OH). This reaction forms the precipitate magnesium ammonium phosphate. She dissolved all the chemicals in measured amounts of water before adding them together.
Mg^2+(aq)+NH^4+(aq)+PO4^3-(aq)+6H2O(l)"Mg(NH4)PO4.6H2O(s)
Gemma weighed out 10g of So White washing powder, dissolved it in water, reacted it with a solution of magnesium sulphate and ammonia solution and filtered out the precipitate formed. When this was dry, she weighed it and used molar masses to calculate how much of her precipitate was P.
1. Use atomic masses to calculate the % of P in Mg(NH4)PO4.6H2O
I worked this out to be combined mass of 245.418, then did the mass of P over the combined mass and multiplied it by 100 ( for %) which was 30.97/245.418 X 100 = 12.62%
2. Gemma found the dry precipitate weighed 4.35g. How much of this 4.35g of Mg(NH4)PO4.6H2O was phosphorus?
Now I have the answer as 0.34g, but out of stupidity didn't write down my working. This question relates to the next few, which my answers seem to be unrealistic and yea. so I was wondering if someone would be able to do it and see what they come up with?
thanx in advance.
Mg^2+(aq)+NH^4+(aq)+PO4^3-(aq)+6H2O(l)"Mg(NH4)PO4.6H2O(s)
Gemma weighed out 10g of So White washing powder, dissolved it in water, reacted it with a solution of magnesium sulphate and ammonia solution and filtered out the precipitate formed. When this was dry, she weighed it and used molar masses to calculate how much of her precipitate was P.
1. Use atomic masses to calculate the % of P in Mg(NH4)PO4.6H2O
I worked this out to be combined mass of 245.418, then did the mass of P over the combined mass and multiplied it by 100 ( for %) which was 30.97/245.418 X 100 = 12.62%
2. Gemma found the dry precipitate weighed 4.35g. How much of this 4.35g of Mg(NH4)PO4.6H2O was phosphorus?
Now I have the answer as 0.34g, but out of stupidity didn't write down my working. This question relates to the next few, which my answers seem to be unrealistic and yea. so I was wondering if someone would be able to do it and see what they come up with?
thanx in advance.