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Shkiper50 [21]
2 years ago
6

A weather balloon filled with helium has a volume of 700 L at STP. To find the mass of helium which conversion factors would you

use
A) 22.4 L/mol x 4 g/mol
B) 700 L / 4 g/mol
C) (22.4 L/mol / 700 L ) / (4 g/mol)
D) (700 L / 22.4 L/mol) (4 g/mol)
Chemistry
1 answer:
Vedmedyk [2.9K]2 years ago
3 0

Answer:

D: (700 L / 22.4 L/mol) (4 g/mol)

Explanation:

At STP, Molar volume of a gas = 22.4 L/mol

Now, we are told that helium has a volume of 700 L at STP.

Also, atomic mass of helium = 4 g/mol

Thus, the mass of helium is given as;

(700 L/22.4 L/mol) × 4 g/mol

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How many grams are in the quantity: 2.5 mol of NaCl
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Answer:

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Explanation:

7 0
3 years ago
Read 2 more answers
How do you solve stoichiometry problems
nataly862011 [7]
Ok so the way I do it is as simple as possible.
Firstly look at the reactants and products ( there can be one reactant and one product or more ) you will usually be given the moles of the reactant or products, if you are given grams you can convert into moles by this convertion ( grams/R.M.M ) where R.M.M is the relative atomic mass of your substance ( the mass number of all of the elements in your substance).

Ok when you have moles now look at the ratio between the products and reactants. Usually you will won't know the moles of one substance therefore you will be asked to find moles or mass of that substance.

For example:

When 16 grams of oxygen and 1 gram of hydrogen gas react to produce water. Find the number of grams of water being produced.

O2 + 2H2 -> 2H2O
16g      2g          xg

Here we're told the mass of the reactants. In stoichiometry we need to work with moles therefore you need to calculate moles of the reactants.
Firstly find the R.M.M of each reactant.
R.M.M of O2 is 16+16=32 since it's diatomic we add atomic masses of two oxygen atoms.
R.M.M of H2 is 1+1=2, it's also diatomic. (Diatomic two atoms of the same element are joined together). (Ignore the number 2 in front of H2, this number shows us the ratio relationship between reactans or products, i.e when we balance an equation.)

Ok so now find moles:

We have 16 grams of O2
16/R.M.M
16/32 = 0.5 moles

We have 2 grams of H2
1/R.M.M
2/2 = 1 mole
Now back to the equation.

O2 + 2H2 -> 2H2O
0.5 moles 1mole xmoles                  (it's xmoles because we don't know                                                               molarity of water that's what we have                                                           find firstly in order to find grams.)
Now look at the ratio between any reactant and product i.e you can choose which reactant to compare to the product, it doesn't make a different ( I will do two or you can do two at the same time)

1st method:
Look at the ratio between O2 and H2O from the reaction above we see the ratio is 1:2 therefore for every 0.5 moles of O2 you get 1 mole of H2O.
1:2
0.5 : x
0.5*2 = 1

2nd method;
Look at the ratio betweem H2 and H2O from the reaction above we see the ratio is 2:2 or 1:1. We have 1 mole of H2 there we must have 1 mole of H2O. We see this is true as both methods give us 1 mole of H2O.

3rd method ( combined):
Look at the ratio between O2, H2 and H2O.
We see that the ratio is 1:2:2
So we have 0.5:1:x
If we multiply 0.5 *2 it equals 1 mole
If we multiply 1*1 we get 1 moles.
Any method is correct and it's up to you to find a comfortable way.
We're not finished in the question we are asked for the mass of water.
So just multiply the number of moles (1mole) by R.M.M of H2O.
1 * R.M.M
R.M.M of H2O = 1+1+16=18
1*18= 18 grams.
And you're finished.

I am sorry if this is so long I want you to understand as much as possible.
In stoichiometry you can also be asked about the empirical formula of a substance. I can show you how do it. If you have any question just tell me.
Hope this helps :).
7 0
3 years ago
Which of these pairs of atoms are isotopes?
Troyanec [42]

Answer:

c

Explanation:

6 0
2 years ago
I really need help with this question please help me.
oksano4ka [1.4K]
I would say A because it’s the only one that doesn’t conduct electricity. Ionic compounds conduct electricity, and covalent compounds do not.
3 0
3 years ago
Given that a for HBrO is 2. 8×10^−9 at 25°C. What is the value of b for BrO− at 25°C?
lara [203]

If Ka for HBrO is 2. 8×10^−9 at 25°C, then the value of Kb for BrO− at 25°C is 3.5× 10^(-6).

<h3>What is base dissociation constant? </h3>

The base dissociation constant (Kb) is defined as the measurement of the ions which base can dissociate or dissolve in the aqueous solution. The greater the value of base dissociation constant greater will be its basicity an strength.

The dissociation reaction of hydrogen cyanide can be given as

HCN --- (H+) + (CN-)

Given,

The value of Ka for HCN is 2.8× 10^(-9)

The correlation between base dissociation constant and acid dissociation constant is

Kw = Ka × Kb

Kw = 10^(-14)

Substituting values of Ka and Kw,

Kb = 10^(-14) /{2.8×10^(-9) }

= 3.5× 10^(-6)

Thus, we find that if Ka for HBrO is 2. 8×10^−9 at 25°C, then the value of Kb for BrO− at 25°C is 3.5× 10^(-6).

DISCLAIMER: The above question have mistake. The correct question is given as

Question:

Given that Ka for HBrO is 2. 8×10^−9 at 25°C. What is the value of Kb for BrO− at 25°C?

learn more about base dissociation constant:

brainly.com/question/9234362

#SPJ4

7 0
1 year ago
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