A sample of hydrogen gas occupies 50.4 L at STP. This sample contains how many moles of hydrogen atoms

I’m confused because this is the answer key and I don’t know how they got the answer to number 1)

Tems11 [23]

Question One

It's more a question of unscrambling what is there. The answer is correct.

If you look at your periodic table, there is such an element as Na which I suspect might be the problem.

It has an atomic mass of 23. It's atomic number is 11 which means it is the 11th member (by mass) on the periodic table. The other 2 are oxygen and hydrogen. So Oxygen has an atomic mass of 16 and Hydrogen has an atomic mass of 1.

Oxygen is number 8 on the periodic table and hydrogen is number 1.

Molecular Mass

Na = 23

O = 16

H = 1

Total 40, just as the answer key says. I've probably given you more than you wanted to know, but if you still have trouble, leave a note.

5 0

3 years ago

Why are all of the substances on the periodic table classified as elements?

natta225 [31]

Because just like compounds, the table of chemicals can be looked at as having all the different pieces of it. So the different chemicals are the different "elements" to the periodic table.

6 0

3 years ago

a sample of cobalt (specific heat of Co=0.418J/G C )at 100.0 C is dropped into a calorimeter containing 500.0 mL of water at 21.

Alex17521 [72]

Answer:

$m_{Co}=6998g=7.0kg$

Explanation:

Hello there!

In this case, according to this equilibrium temperature problem, we can set up the following equation to relate the mass, specific heat and temperature change:

$Q_{Co}=-Q_{w}\\\\m_{Co}C_{Co}(T_f-T_{Co})=-m_{w}C_{w}(T_f-T_{w})$

Thus, we solve for the mass of cobalt as shown below:

$m_{Co}=\frac{-m_{w}C_{w}(T_f-T_{w})}{C_{Co}(T_f-T_{Co})} \\\\m_{Co}=\frac{-500.00g*4.184J/g\°C(67.1\°C-21.1\°C)}{0.418J/g\°C(67.1\°C-100\°C)} \\\\m_{Co}=6998g=7.0kg$

Best regards!

7 0

3 years ago

100 Points!!!!!!!!

Nikitich [7]

your answer is Particles collide in gas so Substance X is a gas.

6 0

3 years ago

Read 2 more answers

A 50.0 mL sample of HCl required 25.81 mL of 0.1250 M KOH for neutralization. What is the molarity of the acid?

topjm [15]

Answer:

0.065M

Explanation:

The reaction expression is given as:

HCl + KOH → KCl + H₂O

Given parameters:

Volume of KOH = 25.81mL = 0.02581L

Molarity of KOH = 0.125M

Volume of HCl = 50mL = 0.05L

Unknown:

Molarity of the acid = ?

Solution:

To find the molarity of the acid, HCl, let us use the mole concept.

First, find the number of moles of the base, KOH;

Number of moles of KOH = molarity of KOH x volume of KOH

Number of moles of KOH = 0.125 x 0.0258 = 0.003225mol

From the balanced reaction equation:

1 mole of KOH reacted with 1 mole of HCl

0.003225mol of KOH will react with 0.003255mole of HCl

Molarity of HCl = $\frac{number of moles of HCl}{Volume of HCl}$

Molarity of HCl = $\frac{0.003255}{0.05}$ = 0.065M

8 0

3 years ago