[sgrant1158]

couple question

1 how many grams of oxygen are in 0.99g of NaHCO3 :   I got   0.189g ( is this correct?)
2 how many moles of hydrogen sulfide are contained in 71.3g of this gas? I got 35.4mol
3 when 143.0g of C2H4 burns in oxygen to give carbon dioxide and water, how many grams of CO2 are formed? I got 224.3g
4 A hydrocarbon is found to be 85.6% carbon by mass, what is the empirical formula? I got CH2
5 ammonia has a mass of 67.5g, how many molecules . I got 1.52e23 molecules
last one
6 15g of lithium is reacted with 15g fluorine to form lithium fluoride, after the reactionis complete what will be present. I got  2.16 moles lithium fluoride only

I need to know if i got these right or my mom will kill me if I don't pass this take home test :-)

thanks to all

Steven

[enahs]

1) Correct.
2) Incorrect.
3) Incorrect.
4) Correct.
5) Incorrect.
6) Incorrect.

[sgrant1158]

Thanks your the best

do you know what the answers are to the other questions?

thanks again

[enahs]

Oops, I lied about #1, it is incorrect.

There are 3 oxygens per NaHCO3.

1) 0.565g (your first answer I accidentally typed as correct was wrong, you just found the % of one oxygen molecule, not all 3), watch your significant figures on this one, it is very important here to illustrate you calculated it correct
2) 2.09 mol (this is just mass/MW)
3)448.6 (notice something about your answer and this one? You are off by a factor 2, you did not balance the equation first)
5) 2.38e24 ( First find moles, and for every mole you have 6.022e23 molecules)
6) 0.789 mol LiF (20.5g) and 1.37 mol Li (9.5g) are left over (You must first convert mass to moles, write a balanced equation and find out which one is your limiting reagent), you can also then check your self after calculating it by converting them to grams (as I did) because you know the masses also have to balance, so 20.5+9.5 = 30 (which is what we started with). Note: your teacher probably wants the answer for that in mass, but you can put both to be sure.