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2 years ago

What is the number of molecules in 9.0 g of steam?

Chemistry

1 answer:

77julia77 [94]2 years ago

4 0

Steam is water (H2O)

The relative molecular mass of water has to be calculated:

Refer to periodic table for molar mass/relative atomic mass for every element

Hydrogen has molar mass of 1g but as it is H2 there are 2 moles so : 2*1g =2g

Oxygen has molar mass of 16g

So relative molecular mass of water equals 18g

To find the number of moles of water in 9g divide mass (9g) by relative molecular mass of water (18g) u get 0.5 moles .

1 mole = 6.03*10^23 particles (in this case molecules)Avogadro's number

So 0.5 *(6.03*10^23)= 3.015*10^23 molecules

9 gram of steam contain 3.015*10^23 H2O molecules.

Note: 9 gram of water whether as ice or liquid water or steam always contains 3.015*10^23 water molecules.

9 grams of ice or liquid water or steam have different volumes but same number of molecules . Probably u need a lot balloons filled with water vapour to get 9 grams whereas u need a small cube of ice to get these 9 grams .Ice is more dense than water vapour.

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How much energy is released when 0.40 mol C6H6(g) completely reacts with oxygen?

Vsevolod [243]

<span>This question asksyou to apply Hess's law.
You have to look for how to add up all the reaction so that you get the net equation as the combustion for benzene. The net reaction should look something like C6H6(l)+ O2 (g)-->CO2(g) +H2O(l). So, you need to add up the reaction in a way so that you can cancel H2 and C.
multiply 2 H2(g) + O2 (g) --> 2H2O(l) delta H= -572 kJ by 3
multiply C(s) + O2(g) --> CO2(g) delta H= -394 kJ by 12
multiply 6C(s) + 3 H2(g) --> C6H6(l) delta H= +49 kJ by 2 after reversing the equation.
Then,
6 H2(g) + 3O2 (g) --> 6H2O(l) delta H= -1716 kJ
12C(s) + 12O2(g) --> 12CO2(g) delta H= -4728 kJ
2C6H6(l) --> 12 C(s) + 6 H2(g) delta H= - 98 kJ
______________________________________...
2C6H6(l) + 16O2 (g)-->12CO2(g) + 6H2O(l) delta H= - 6542 kJ
I hope this helps and my answer is right.</span>

4 0

3 years ago

Read 2 more answers

How many visible impact craters does the moon contain?

frez [133]

I believe the answer is B. a million or more.

5 0

3 years ago

When 7.085 grams of a hydrocarbon, CxHy, were burned in a combustion analysis apparatus, 21.71 grams of CO2 and 10.37 grams of H

Taya2010 [7]

Answer:

- Empirical:

$C_3H_7$

- Molecular:

$C_6H_{14}$

Explanation:

Hello,

In this case, based on the information regarding the combustion, the moles of carbon turn out:

$n_C=21.71gCO_2*\frac{1molCO_2}{44gCO_2}*\frac{1molC}{1molCO_2}=0.493molC$

Moreover, the moles of hydrogen:

$n_H=10.37gH_2O*\frac{1molH_2O}{18gH_2O}*\frac{2molH}{1molH_2O}=1.152molH$

Thus, the subscripts of carbon and hydrogen in the hydrocarbon turn out:

$C=\frac{0.4934}{0.4934}=1\\H=\frac{1.15222}{0.4934}=2.335\\CH_{2.335}$

Now, looking for a suitable whole number we obtain the following empirical formula as 2.335 times 3 is 7 for hydrogen:

$C_3H_7$

In such a way, that compound has a molar mass of 43 g/mol, thus, the whole compound's molar mass is 86.18 g/mol for which the molecular formula is twice the empirical one, therefore:

$C_6H_{14}$

Which is hexane.

Best regards.

6 0

3 years ago

What is the primary reason why elements form compounds?

zheka24 [161]

Answer:

To gain stability

Explanation:

If the outermost shell is not completely filled with electrons, the element has one of the three options: gaining electrons, losing electrons or sharing electrons. By gaining or losing electrons, ionic compounds are produced. Sharing of electrons results in the formation of covalent compounds.

6 0

3 years ago

A small portion of a crystal lattice is sketched below. What is the name of the unit cell of this lattice? Your answer must be a

Nikolay [14]

This is an incomplete question, the given sketch is shown below.

Answer : The name of given unit cell is, FCC (face-centered cubic unit cell)

Explanation :

Unit cell : It is defined as the smallest 3-dimensional portion of a complete space lattice which when repeated over the and again in different directions produces the complete space lattice.

There are three types of unit cell.