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3 years ago

How do I calculate the standard enthalpy change for the following reaction at 25 °C ?

1 answer:

4 0

MgCl2(s) + H2O(l) → MgO(s) + 2 HCl(g)

Using the standard enthalpies of formation given in the source below:

(−601.24 kJ) + (2 x −92.30 kJ) − (−641.8 kJ) − (−285.8 kJ) = +141.76 kJ
So:

MgCl2(s) + H2O(l) → MgO(s) + 2 HCl(g), ΔH = +141.76 kJ

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Draw the lewis structure of ch3nc; fill in any nonbonding electrons. Calculate the formal charge on each atom other than hydroge

jenyasd209 [6]

A visual representation of covalent bonding which represents the valence shell electrons in the molecule is said to be a Lewis structure. The lines represents the shared electron pairs and dots represents the electrons that are not involved in the bonding i.e lone pairs.

Number of valence electrons in each atom:

For Carbon, $C$ = 4

For Hydrogen, $H$ = 1

For Nitrogen, $N$ = 5

The Lewis structure of $CH_3NC$ is shown in the attached image.

The formula of calculating formula charge = $FC = VE - NE- \frac{BE}{2}$ -(1)

where, F.C is formal charge, V.E is number of valence electrons, N.E is number of non-bonding electrons and B.E is number of bonding electrons.

Now, calculating the formal charge:

For $C$ on left side:

$FC = 4 - 0- \frac{8}{2} = 0$

For $N$ :

$FC = 5 - 0- \frac{8}{2} = +1$

For $C$ on right side:

$FC = 4 - 2- \frac{6}{2} = -1$

The formula charge of each atom other than hydrogen is shown in the attached image.

6 0

2 years ago

What is the mass in grams of 2.8 x 10^19 formula units of beryllium nitrate

makkiz [27]

To convert the formula unit to mass, we need to divide the given formula units by Avogadro's number, 6.022 x 10^23 and we get the mole of beryllium nitrate. To convert to mass, we need to multiply the number of moles with the molecular formula of the compound which is 133.022 g/mol.The answer is 0.006185 g or 6.185 mg.

5 0

2 years ago

Can yall assist me with this lab? It is really screwing me up... No spam!! the only part that I need is the last page. I will ma

kenny6666 [7]

Answer:

What do you need help with?!

Explanation:

5 0

1 year ago

The most reactive metals are located in which area of the periodic table?

SCORPION-xisa [38]

The answer is b.Far left

8 0

2 years ago

Three common gaseous compounds of nitrogen and oxygen of different elementary composition are known: (A) laughing gas containing

Ede4ka [16]

Answer:

Please find how these data prove the law of multiple proportions below

Explanation:

The law of multiple proportions was proposed by an English chemist called John Dalton. The law states that when two elements combine and to form more than one compound. The weights/masses of the second element in the two compounds, which combines with a fixed ratio of the first element, is in a simple whole number ratio.

In this question, Nitrogen is said to combine with oxygen to give three different compounds as follows:

A) laughing gas containing 63.65% nitrogen i.e. 0.6365g

This means that the mass of oxygen will be (1-0.6365) = 0.3635g

B) colorless gas containing 46.68% nitrogen i.e. 0.4668g

This means that the mass of oxygen will be 0.5332g

C) brown toxic gas containing 30.45% nitrogen i.e. 0.3045g

This means that the mass of oxygen will be 0.6955g

The ratios of oxygen in the three compounds is therefore:

0.3635: 0.5332: 0.6955

Divide this ratio by the smallest number (0.3635)

0.3635/0.3635 = 1

0.5332/0.3635 = 1.467

0.6955/0.3635 = 1.913

Multiply this ratio by 2, we have:

2: 2.9 : 3.8

Hence, the simple whole number ratio is 2:3:4.

This proves the law of multiple proportions that oxygen is in simple whole number ratio in the three different compounds.

4 0

2 years ago