Question

When magnesium metal and an aqueous solution of hydrochloric acid combine, they produce an aqueous solution of magnesium chloride and hydrogen gas. Using the equation, Mg (s) + 2HCl (aq) arrow MgCl2 (aq) + H2 (g), if 24.3 g of Mg and 75.0 g of HCl are allowed to react, calculate the mass of H2 that is produced.

Answer 1

@Preetha

Answer 2

@dan815

Answer 3

@1800_RATCHETHUNTERS

Answer 4

idk mane

Answer 5

fine, fine...:)

Answer 6

Can you calculate the number of moles first?

Answer 7

for what?

Answer 8

For 24.3 grams of magnesium and 75.0 grams of hydrochloric acid?

Answer 9

yes, I'm trying to figure that out now
finding molar mass confuses me

Answer 10

my friend's dad, who's a chemical engineer, says it's atomic weight?

Answer 11

yup

Answer 12

ok....but for 2HCI..do I find the atomic weights of H and CI, add them, and multiply the sum to find the molar mas?

Answer 13

sorry, multiply the sum by 2

Answer 14

do not multiply the sum by anything.

You have 75 grams of HCl.
One mole of HCl has ? grams.

The number of moles of HCl, thus, is 75/?

Answer 15

since it's 2HCI

Answer 16

ohhh....ok...
so I need to find how many grams HCI has

Answer 17

brb

Answer 18

H = 1 gram.
Cl = 35.45 grams.

Answer 19

k..so that makes it
75/(1 + 35.45)

Answer 20

75/(36.45)

Answer 21

2

Answer 22

HCI's molar mass is 2?

Answer 23

No, the number of moles of HCl is 2.

Answer 24

oh, right, right

Answer 25

MG wouldn't happen to have one mole would it?

Answer 26

It would, because the mass of one mole of Mg is 24.3 g (that's the definition of molar mass).

Answer 27

woohoo
OK, now I have to find out what the original question was, lol :)
thnx btw for your help

Answer 28

Now that you have the number of moles, do you know how to analyse reactions?

I'll give you a simple example.\[\rm 2Mg + O_2 \to 2MgO\]This means that for every two moles of Mg and every one mole of O, you get two moles of MgO.

Answer 29

OK...

Answer 30

So in our reaction, can you think of the number of moles of \(\rm H_2\) using the same logic?

Answer 31

ummm.....one....?

Answer 32

it can't be more than 3 can it?

Answer 33

so it has to be either one or two...I would imagine..
my brain does not want to process this...work, dammit, WORKK!!

Answer 34

\[\rm Mg + 2HCl \to MgCl_2+H_2\]If you have one mole of magnesium and two moles of hydrochloric acid, you're gonna get one mole of \(\rm MgCl_2\) and one mole of \(\rm H_2\). Do you understand why that is?

Answer 35

well...kinda...I would have expected that you'd get 2 moles of MgCI2 though...

Answer 36

Here is how I understood this:

First, clear your mind.

Second, think about this carefully:

If one molecule of Mg reacts with two molecules of HCl, then you would get one molecule of \(\rm MgCl_2\) and one molecule of \(\rm H_2\).

Do you agree with the above to start with?