express this mass as a percentage of the weight of your sample of plant food. this is the % of elemental phosphorous in the plant food.
I'm not sure what the question is asking for. The mass its referring to is 0.06438g Phosphorus and the weight of the plant food is 1.007g.
(Mass P/mass sample)*100 = %
ok and i had another question:
convert that to the % phosphorus present as phosphorous pentoxide (P2O5)
%P2O5 = %P x (molar mass P2O5/2*atomic mass P) = ??
To express the mass of phosphorous as a percentage of the weight of your sample of plant food, you need to calculate the ratio between the mass of phosphorous and the weight of the plant food, and then multiply that ratio by 100 to get the percentage.
Here's how you can do it:
1. Calculate the ratio:
Mass of phosphorous / Weight of plant food
0.06438 g / 1.007 g = 0.0639
2. Multiply the ratio by 100 to obtain the percentage:
0.0639 * 100 = 6.39%
Therefore, the mass of phosphorous represents 6.39% of the weight of the sample of plant food.