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3 years ago

According to its periodic table entry, how many electrons does nitrogen have in its valence level?

1 answer:

3 0

The valence level of an atom refers to the number of electrons that reside in the upper most energy level. Nitrogen has an atomic number of 7 and therefore has 7 electrons. The first energy level (1) holds 2 electrons, leaving 5 electrons to reside in the second energy level (2s and 2p). Therefore the valence of nitrogen is 5.

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Before a child takes a bath, his mother mixes bubbles into bath water. Physical or Chemical Change?

NeX [460]

Answer:

chemical

Explanation:

6 0

3 years ago

Combustion reactions are exothermic. The heat of reaction for the combustion of 2-methylheptane, C8H18, is 1.306×103 kcal/mol. W

WARRIOR [948]

Answer:

11.45kcal/g

2.612 × 10³ kcal

Explanation:

When a compound burns (combustion) it produces carbon dioxide and water. The combustion of 2-methylheptane can be represented by the following balanced equation:

2 C₈H₁₈ + 25 O₂ ⇄ 16 CO₂ + 18 H₂O

It releases 1.306 × 10³ kcal every 1 mol of C₈H₁₈ that is burned.

What is the heat of combustion for 2-methylheptane in kcal/gram?

We know that the molar mass of C₈H₁₈ is 114.0g/mol. Then, using proportions:

$\frac{1.306 \times 10^{3}Kcal}{1mol} .\frac{1mol}{114.0g} =11.45kcal/g$

How much heat will be given off if molar quantities of 2-methylheptane react according to the following equation? 2 C₈H₁₈ + 25 O₂ ⇄ 16 CO₂ + 18 H₂O

In this equation we have 2 moles of C₈H₁₈. So,

$2mol \times\frac{1.306 \times 10^{3}kcal }{1mol} =2.612\times 10^{3}kcal$

3 0

2 years ago

A 2.40 kg block of ice is heated with 5820 J of heat. The specific heat of water is 4.18 J•g^-1•C^-1. By how much will it’s temp

MrMuchimi

Answer: The temperature rise is $0.53^0C$

Explanation:

The quantity of heat required to raise the temperature of a substance by one degree Celsius is called the specific heat capacity.

$Q=m\times c\times \Delta T$

Q = Heat absorbed by ice = 5280 J

m = mass of ice = 2.40 kg = 2400 g (1kg=1000g)

c = heat capacity of water = $4.18J/g^0C$

Initial temperature = $T_i$

Final temperature = $T_f$

Change in temperature , $\Delta T=T_f-T_i=?$

Putting in the values, we get:

$5280J=2400g\times 4.18J/g^0C\times \Delta T$

$\Delta T=0.53^0C$

Thus the temperature rise is $0.53^0C$

0 0

3 years ago

The value of ΔG° at 221.0°C for the formation of phosphorous trichloride from its constituent elements, P2(g) + 3Cl2(g) → 2PCl3(

densk [106]

Answer:

ΔG = - 590.20 kJ/mol

Explanation:

The formula for calculating Gibb's Free Energy can be written as:

ΔG = ΔH - TΔS

Given That:

ΔH = -720.5 kJ/mol

T = 221.0°C = (221.0 + 273.15) = 494.15 K

ΔS° = -263.7 J/K

So; ΔS° = -0.2637 kJ/K if being converted from joule to Kilo-joule

Since we are all set, let replace our given data in the above equation:

ΔG = (-720.5 kJ/mol) - (494.15 K) ( - 0.2637 kJ/K)

ΔG = (-720.5 kJ/mol) - (- 130.30755)

ΔG = -720.5 kJ/mol + 130.30755

ΔG = -590.192645 kJ/mol

ΔG = - 590.20 kJ/mol

Thus, The value of ΔG° at 221.0°C for the formation of phosphorous trichloride from its constituent elements, P2(g) + 3Cl2(g) → 2PCl3(g) is -590.20 kJ/mol.

3 0

2 years ago

Hydrogen iodide can decompose into hydrogen and iodine gases. 2 HI(g) H2(g) + 12(g) Kp for the reaction is 0.016. If 0.350 atm o

solniwko [45]

Answer : The total pressure at equilibrium is 0.350 atm

Solution : Given,

Initial pressure of $HI$ = 0.350 bar