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2 years ago

How much energy is absorbed when 15g of water at 100C boiled away?

Chemistry

1 answer:

creativ13 [48]2 years ago

4 0

Answer:

∴ Q = m·ΔHv = 15g x 540 cals/g = 8100 calories = 33,890 joules

Explanation:

Phase transition formula => Q = m·ΔHv

Q = amount of heat absorbed

ΔHv = Heat of vaporization = 540 cal/g = 25,594 joules/g at 100°C

m = mass of substance = 15 grams

∴ Q = m·ΔHv = 15g x 540 cals/g = 8100 calories = 33,890 joules

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1. What pressure would be exerted by 46.0grams of hydrogen gas placed into a 3.00 L container at

dlinn [17]

Answer:

187.34 atm

Explanation:

From the question,

PV = nRT.................. Equation 1

Where P = Pressure, V = Volume, n = number of mole, R = molar gas constant, T = Temperature.

make P the subject of the equation

P = nRT/V.............. Equation 2

n = mass(m)/molar mass(m')

n = m/m'............... Equation 3

Substitute equation 3 into equation 2

P = (m/m')RT/V............ Equation 4

Given: m = 46 g, T = 25°C = (25+273) = 298 K, V = 3.00 L

Constant: m' = 2 g/mol, R = 0.082 atmL/K.mol

Substitute these values into equation 4

P = (46/2)(0.082×298)/3

P = (23×0.082×298)/3

P = 187.34 atm

3 0

2 years ago

A compound is found to contain 37.32 % phosphorus , 16.88 % nitrogen , and 45.79 % fluorine by

Alla [95]

Answer: 1. The empirical formula is $PNF_2$

2. The molecular formula is $PNF_2$

Explanation:

If percentage are given then we are taking total mass is 100 grams.

So, the mass of each element is equal to the percentage given.

Mass of P = 37.32 g

Mass of N = 16.88 g

Mass of F = 45.79 g

Step 1 : convert given masses into moles.

Moles of P = $\frac{\text{ given mass of P}}{\text{ molar mass of P}}= \frac{37.32g}{31g/mole}=1.20moles$

Moles of N = $\frac{\text{ given mass of N}}{\text{ molar mass of N}}= \frac{16.88g}{14g/mole}=1.20moles$

Moles of F = $\frac{\text{ given mass of F}}{\text{ molar mass of F}}= \frac{45.79g}{19g/mole}=2.41moles$

Step 2 : For the mole ratio, divide each value of moles by the smallest number of moles calculated.

For P = $\frac{1.20}{1.20}=1$

For N = $\frac{1.20}{1.20}=1$

For F = $\frac{2.41}{1.20}=2$

The ratio of P: N: F= 1: 1: 2

Hence the empirical formula is $PNF_2$

The empirical weight of $PNF_2$ = 1(31)+1(14)+2(19)= 82.98 g.

The molecular weight = 82.98 g/mole

Now we have to calculate the molecular formula.

$n=\frac{\text{Molecular weight}}{\text{Equivalent weight}}=\frac{82.98}{82.98}=1$

The molecular formula will be= $1\times PNF_2=PNF_2$

3 0

3 years ago

Write a balanced chemical equation for the standard formation reaction of liquid chloroform (CHCI).

Inga [223]

<u> C^1H^1C^1I^1</u>

Explanation:

<u>this seems already balanced</u>

C = 1

H =1

C = 1

I = 1

8 0

2 years ago

Determine whether a precipitate will form when 0.96g of Na2CO3 is combined with 0.20g BaBr2 in a 10 L solution.

Mashcka [7]

Answer:

Qsp > Ksp, BaCO3 will precipitate

Explanation:

The equation of the reaction is;

Na2CO3 + BaBr2 -------> 2NaBr + BaCO3

Since BaCO3 may form a precipitate we can determine the Qsp of the system.

Number of moles of Na2CO3 = 0.96g/106 g/mol = 9.1 * 10^-3 moles

concentration of NaCO3 = number of moles/volume of solution = 9.1 * 10^-3 moles/10 L = 9.1 * 10^-4 M

Number of moles of BaBr2 = 0.20g/297 g/mol = 6.7 * 10^-4 moles

concentration of BaBr2 = 6.7 * 10^-4 moles/10 L = 6.7 * 10^-5 M

Hence;

[Ba^2+] = 6.7 * 10^-5 M

[CO3^2-] = 9.1 * 10^-4 M

Qsp = [6.7 * 10^-5] [9.1 * 10^-4]

Qsp = 6.1 * 10^-8

But, Ksp for BaCO3 is 5.1*10^-9.

Since Qsp > Ksp, BaCO3 will precipitate

3 0

3 years ago

The atmospheric pressure at sea level is greater than on Mount Everest

statuscvo [17]

This statement is true in fact to mount Everest atmospheric pressure sit at about one third of that at sea level.

5 0

3 years ago