Question

In the explosion of a hydrogen-filled balloon, 0.90g of hydrogen reacted with 7.2g of oxygen. How many grams of water vapor are formed? (Water vapor is the only product.)

Answer 1

what is the reaction equation?

Answer 2

what?

Answer 3

Do you even know what a reaction equation is?

Answer 4

No, the product is water

Answer 5

A reaction equation is something like this:

\(\sf\large reactant\ 1+reactant\ 2\to product\)

Answer 6

Can't say the person who helped you with your previous question did a good job.

Answer 7

\(\sf\large hydogen+oxygen\to water\)

Answer 8

ok

Answer 9

i get that know

Answer 10

Do you know the chemical formulas for hydrogen, oxygen and water?

Answer 11

yes

Answer 12

So what are they?

Answer 13

no wait i am stuck

Answer 14

can you tell me and ill take notes

Answer 15

plesase

Answer 16

Hydrogen = \(\sf H_2\)
Oxygen = \(\sf O_2\)
Water = \(\sf H_2O\)

put those in the equation and you'll get:

\(\sf H_2+O_2\to H_2O\)

Now we have to balance the equation so that there are an equal amount of H's and O's on both sides of the arrow. Any idea how to do that?

Answer 17

No.
On the left there are 2 O's and on the right there is only 1 O

Answer 18

OK

Answer 19

How about the H's?

Answer 20

1 ON BOTH SIDE

Answer 21

no, 2 on both sides

Answer 22

NO SRRY YES THAT IS WHAT I MEANT

Answer 23

So the problem is the Oxygen.
how about we add a 2 before hydrogen

\(\sf H_2+O_2\to 2H_2O\)

is everything right now?

Answer 24

yes

Answer 25

im not lost

Answer 26

Count the O's on the left and on the right. Are they the same?
Then do the same for the H's

Answer 27

yes

Answer 28

So how many O's and H's are on both sides?
I need you to show some effort, I'm not here to give you the answer. You're here because you want to learn how to do this right? Or do you only want the answer?

Answer 29

there are two hydrogen and oxygen in both sisdes

Answer 30

2H2O means 2 times H2 which is 4 H's

Answer 31

So we have the oxygen equal. the hydrogen is 2 on the left, 4 on the right. how do we fix that?

Answer 32

put the rigt to the left

Answer 33

no

Answer 34

bring the 4 hydroge on the righ and put it in front of the oxygen

Answer 35

how do we do that

Answer 36

we add a coefficient before the H2 on the left side.
1x H2 = 2 H's
2x H2 = 4 H's

So the coefficient is 2.
Simply put a 2 before H2 on the left side so the equation will be:

\(\sf 2H_2+O_2\to 2H_2O\)

Now there are 4 H's and 2 O's on both sides which means the equation is "balanced"

Answer 37

ok

Answer 38

makes sense

Answer 39

now what next

Answer 40

Now that we know the reaction equation, the next step is converting the amounts of reactants to moles.

Any idea how to convert 0.90 gram hydrogen to mol hydrogen?

Answer 41

is it 0.8929102922793023

Answer 42

if no then i dont

Answer 43

if that not right

Answer 44

To convert grams to mole. you have to divide by the molar weight of hydrogen. what is the molar weight of hydrogen? you can find it on a periodic table like http://ptable.com

Answer 45

1.01

Answer 46

show your work

Answer 47

1.01 is the moler weight of hydrogen

Answer 48

that all i can do

Answer 49

the molar weight of hydrogen is 1.008 gram/mol

now divide the mass of hydrogen by 1.008 to get the amount of moles

Answer 50

.8928571428571429

Answer 51

right

Answer 52

But we don't have H, we have H2.
So the molar weight is not 1.008 but 2.016

Answer 53

0.4464285714285714

Answer 54

right

Answer 55

right.
Now do the same for oxygen

Answer 56

oxygen moar weight is 15.9994 right

Answer 57

yes that's the molar mass of an oxygen atom, so what's the molar weight of an oxygen molecule?

Answer 58

7.2 g

Answer 59

Oxygen atom = O
Oxygen molecule = O2
just 2*15.9994

Answer 60

31.9988

Answer 61

Yes 31.9988 gram/mol. now we have 7.2 gram oxygen molecules
how many moles is that?

Answer 62

0.2250084378164181

Answer 63

right

Answer 64

Yes
So we have 0.446 mol H2 and 0.225 mol O2

The ratio of the equation is: 2:1->2
2 mol H2 reacts with 1 mol O2 to produce 2 mol H2O

Now we have to find the limiting reactant. This is the reactant that determines how much of the other (excessive) reactant is used in this reaction. The limiting reactant is fully used. Which of the reactants is the limiting reactant?

Answer 65

is it oxygen

Answer 66

Yes. we only have 0.22 mol oxygen and in the ratio only 1 mol oxygen is used and 2 mol hydrogen. which means we need the double amount in mol hydrogen (which is 2x0.22 = 0.44)
This is exactly the amount of moles hydrogen we have so both reactants are fully used.
Now we calculate how many moles H2O we get from this reaction.
we do this by taking the limiting reactant (oxygen) and the ratio of the limiting reactant and the product.
This ratio is 1:2
1 mol oxygen is used to produce 2 mol water vapor
but we only have 0.22 mol oxygen. how many mol water vapor can we produce with that?

Answer 67

i dont know that

Answer 68

1 mol oxygen = 2 mol water vapor
0.22 mol oxygen = ? mol water vapor

Answer 69

3 i guess

Answer 70

Well that's a very strange guess.
The only think you have to do is multiply it by 2

Answer 71

.44 srry

Answer 72

Yes,
now the last step is to convert 0.44 mol H2O to grams
any ideas?

Answer 73

give me steps

Answer 74

Just the reverse of what we did to convert grams to moles. multiply by molar mass.
what is the molar mass of H2O?

Answer 75

2.0158

Answer 76

how is that possible? the mass of 1 oxygen atom is already 16 gram/mol

Answer 77

correct me please

Answer 78

Do determine the molar mass of a compount, just break it into pieces.
We can break H2O in 2 pieces. 2x H and 1x O
just take the molar mass of H and multiply it with 2
then take the molar mass of O and add it to the H's

Answer 79

ok

Answer 80

so hydrogen is 2.01588 when multiplied by two and the moler mass of oxygen is 31.9988

Answer 81

hydrogen is 1.008
we're talking about atoms here. not molecules so only 1 H

Answer 82

2* H= 2*1.008 = 2.016
1* O= 1*15.9994= 15.9994
------+

Answer 83

i will understand this if you jusr do it and then explain after the problem

Answer 84

just add 2.016 and 15.9994...

Answer 85

18.01

Answer 86

right

Answer 87

Yes. now multiply that with the amount of moles H2O we have and you'll have the answer

Answer 88

again how much h20 moles

Answer 89

we just calculated that, are you even trying to understand this?
scroll back up to see it

Answer 90

yes

Answer 91

2.01588

Answer 92

is that the mole

Answer 93

no... 0.22 gram/mol

Answer 94

of h20

Answer 95

0.22 is the mole

Answer 96

yes but we have 2 mol h2o in the equation right?
So that would be 0.44 mol H2O

Now just multiply that with the molar mass of water to get the grams

Answer 97

7.9244

Answer 98

right