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3 years ago

Why do you think that different substances have different melting and boiling pointeds

1 answer:

5 0

The boiling point and melting point of substances is determined by their molecular weight and the cohesion (stickiness) of the individual molecules in the substance.

Based on the cohesive molecule - molecule interactions of a substance, it may have either a high melting and boiling point or vice versa. The stronger the cohesive interactions the more the heat required for the substance's transition into liquid and gas state.

These intermolecular forces include hydrogen bonding , ionic bonding, dipole dipole, and Van Der Waals dispersion forces.

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Given these reactions, where X represents a generic metal or metalloid 1 ) H 2 ( g ) + 1 2 O 2 ( g ) ⟶ H 2 O ( g ) Δ H 1 = − 241

anygoal [31]

Answer : The enthalpy of the given reaction will be, -1048.6 kJ

Explanation :

According to Hess’s law of constant heat summation, the heat absorbed or evolved in a given chemical equation is the same whether the process occurs in one step or several steps.

The main reaction is:

$XCl_4(s)+2H_2O(l)\rightarrow XO_2(s)+4HCl(g)$ $\Delta H=?$

The intermediate balanced chemical reactions are:

(1) $H_2(g)+\frac{1}{2}O_2(g)\rightarrow H_2O(g)$ $\Delta H_1=-241.8kJ$

(2) $X(s)+2Cl_2(g)\rightarrow XCl_4(s)$ $\Delta H_2=+461.9kJ$

(3) $\frac{1}{2}H_2(g)+\frac{1}{2}Cl_2(g)\rightarrow HCl(g)$ $\Delta H_3=-92.3kJ$

(4) $X(s)+O_2(g)\rightarrow XO_2(s)$ $\Delta H_4=-789.1kJ$

(5) $H_2O(g)\rightarrow H_2O(l)$ $\Delta H_5=-44.0kJ$

Now reversing reaction 2, multiplying reaction 3 by 4, reversing reaction 1 and multiplying by 2, reversing reaction 5 and multiplying by 2 and then adding all the equations, we get :

(1) $2H_2O(g)\rightarrow 2H_2(g)+O_2(g)$ $\Delta H_1=2\times 241.8kJ=483.6kJ$

(2) $XCl_4(s)\rightarrow X(s)+2Cl_2(g)$ $\Delta H_2=-461.9kJ$

(3) $2H_2(g)+2Cl_2(g)\rightarrow 4HCl(g)$ $\Delta H_3=4\times -92.3kJ=-369.2kJ$

(4) $X(s)+O_2(g)\rightarrow XO_2(s)$ $\Delta H_4=-789.1kJ$

(5) $2H_2O(l)\rightarrow 2H_2O(g)$ $\Delta H_5=2\times 44.0kJ=88.0kJ$

The expression for enthalpy of main reaction will be:

$\Delta H=\Delta H_1+\Delta H_2+\Delta H_3+\Delta H_4+\Delta H_5$

$\Delta H=(483.6)+(-461.9)+(-369.2)+(-789.1)+(88.0)$

$\Delta H=-1048.6kJ$

Therefore, the enthalpy of the given reaction will be, -1048.6 kJ

4 0

3 years ago

A dog whistle has a high frequency. What can you infer about the dog whistle?

zloy xaker [14]

Answer: It would have a high pitch.

Explanation: since the whistle has a high frequency, I can infer that it will have a high pitch.

8 0

3 years ago

Read 2 more answers

A compound contains 30. percent sulfur and 70. percent fluorine by mass. the empirical formula of the compound is

iogann1982 [59]

Assume 100 g of compound. This turns percent to mass. Calculate moles:

S ---> 30/32 = 0.9375
F ---> 70 / 19 = 3.6842

get whole number ratio:

0.9375 / 0.9375 = 1
3.6842 / 0.9375 = 3.93 = 4

Answer : SF4

7 0

3 years ago

Read 2 more answers

How many grams of CaCl2would be dissolved in 1.0 L of a 0.10M<br> solution of CaCl2?

Goryan [66]

Mass of CaCl2=11g
I hope this one is help you

3 0

3 years ago

Will the pH of your stomach increase after sucking antacid tablets?

zlopas [31]

Yes the ph of your stomach will increase after sucking acid tablets

5 0

3 years ago