Chemistry. I need help so bad. ): URGENT and points awarded.?

Question

Please help with all of the questions or just the one.


a) What is the mass of 1.5 moles of water molecules?

b) How many moles are there in 128g of sulphur dioxide (SO2)?


c) When zinc is added to a solution of lead nitrate, lead is displaced from the lead nitrate and zinc nitrate is produced. If 103.5g of lead is displaced, what mass of zinc must have been added?
(Write a balanced chemical equation first)


Thanks

Answer 1

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a) gram molecular mass of water = 16+2 = 18

mass of 1.5 moles of water = 1.5 x 18 = 27 grams

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b)gram molecular mass of sulphur dioxide = 32+ 2 x 16 = 32+32 = 64

no of moles in 128g of sulphur dioxide = 128/64 = 2 moles

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c) Pb(NO3)2 + Zn ----->Zn(NO3)2 + Pb

mass of 1 mole of lead = gram atomic mass of lead =207g

no of moles in 103.5g of Lead = 103.5/207 = 0.5 moles

no of moles of zinc required to displace 1/2 mole of lead = 1/2 moles [from equation, Pb : Zn = 1 : 1]

Mass of Zinc added = 1/2 x gram atomic weight = 1/2 x 65.38 = 32.69g

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Answer 2

a) Well you should know that Moles = Mass / Molar Mass

Therefore, Mass = Moles * Molar Mass

Mass (H2O) = 1.5 * (16 + 2) = 27g of water.



b) You should know that Moles = Mass / Molar Mass

Therefore, Moles (SO2) = 128 / (32.01 + 16 * 2) = 2 moles.



c) Balanced Equation is:

Zn + 2PbNO3 --> 2Pb + Zn(NO3)2



First step, calculate the amount of Lead displaced (in mols)

Use Moles = Mass / Molar Mass.

Moles (Pb) = 103.5 / 207.2 = 0.5 mols



Now, looking at the balanced equation, you can see that 1 mol of Zinc reacts to form 2 mols of Pb; the ratio is 1:2



So in this reaction, 0.5 mols of Pb is formed from 0.25 moles of Zinc ( 0.5 / 2)



Now that we have moles of Zinc, we can use the same mole equation to find out the mass of zinc required.



Mass (Zn) = 0.25 * 65.41 = 16.353g of zinc must be added.

Answer 3

a) Mass of 1.5 moles of water molecules = 1.5 moles X 18 g/mole

= 27 g (Answer)



b) No. moles in 128g of sulphur dioxide = 128g/32gpermole

= 4 mole (Answer)





c) Zn + Pb(NO3)2 --------> Zn(NO3)2 + Pb



Mass of Zn = At.mass of Zn/At. mass of Pb X Mass of Pb

=65/207 X 103.7g

= 32.5 g (Answer)

Answer 4

moles = mass X rfm or ram

so - mass = moles / rfm

1.5/18 = 0.083g

(divide by 18 because H2O = 18. H=1 and O=16)



moles =massXrfm

128 X (32+16+16) = 8192 moles but this seems like a lot i think i did it right but it is a lot of moles are you sure the question is right?



as for part c im not sure sorry

Answer 5

a) no. of mole = weight by gm / molecular weight

1.5 = weight /18

weight = 27 gm

b) no. of mole = 128 / 64(S=32 & O=16)

= 2 mole

c)Pb(NO3)2 +Zn ----------------> Zn(NO3)2 +Pb

207 65

103.5 x

x =103.5*65 /207 =32.5 gm

Answer 6

a) 1.5 mol = x / 18



x = 27g



b) 128 / 64 = 2 moles



c) Zn + Pb(NO3)2 ---> Zn(NO3)2 + Pb



try solving it :D take it as a challenge lol.

Answer 7

Stop asking people to do homework for you!