[sundrops]

The green pigment chlorophyll a, absorbs red light, the energy from which powers photosynthetis processes in plants and algae.

Chlorophyll a is 6.27% nitrogen by mass.
Each molecule of chlorophyll a contains 4 nitrogen atoms.

What is the molecular mass of chlorophyll a?

I'm really confused, I don't even know how tio attack this question - I mean I don't know what chlorophyll is made up of - it doesn't seem like there's enough info. Please *delete me*

[Mitch]

What is the mass of 4 Nitrogens?

[sundrops]

mass of 4 nitrogens would be 14.01 * 4 = 56.04g
right? but how does that help me?

[Mitch]

That was the mass of 6.27% of the molecule.
What is the mass of the other 93.73% of the molecule? Then calculate the total mass for 1 molecule.

[sundrops]

OH! that makes sense! but the mass of the rest of the rest of the molecule isn't given! thats what makes this question sooo hard! not enough information. its frusterating!!

[sundrops]

how do i find the mass of the other 93.73% of the molecule?

[AWK]

6.27/56.04 = 100/x
where x is the molecular mass of chlorophyl

[sundrops]

oh - that makes sense  
thanks so much!

[sundrops]

now what if the chlorophyll molecule contains 1 magnesium atom.
what mass of magnesium is to be found in 2.97 g of chlorophyll?

[sundrops]

how would i go about trying to solve that?

[Mitch]

It wouldn't matter.

[sundrops]

but that's part II of the question - i need to figure it out somehow. I need to find out how much magnesium is in 2.97 g of chlorophyll - how would i go about doing that?

[dexangeles]

you already have the total mass of chlorophyl, so the mass of 1 magnesium atom is what percent of that total mass?

start from there  

[sundrops]

ok so if percent nitrogen is 6.27% and the mass of nitrrogen is 56.04g

then with the mass of 1 magnesium atom being 24.31g - then it's percentage of the total mass would be 2.72% !!

that makes sense!

[sundrops]

now, how would I apply that information into determinig how much magnesium I would find in 2.97g of chlorophyll?