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olga55 [171]
3 years ago
9

A sample of iron with a mass of 200g releases 9840 cal when it freezes at it’s freezing point. What is the molar heat of fusion

for iron?
Chemistry
2 answers:
antoniya [11.8K]3 years ago
8 0

Answer:-

2747.7 Cal mol -1

Explanation:-

Molar heat of Fusion is defined as the amount of heat necessary to melt (or freeze) 1 mole of a substance at its melting point.

Atomic mass of Iron = 55.845 g mol-1

Mass of Iron = 200 g

Number of moles of Iron = 200 g / (55.845 g mol-)

= 3.581 moles

Heat released = 9840 Cal

Molar heat of Fusion = Heat released / Number of moles

= 9840 Cal / 3.581 moles

= 2747.7 Cal mol -1

____ [38]3 years ago
5 0

Answer:

A. 2,747.7 cal/mol

Explanation:

I have several degrees

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The partial pressure of N2 in a mixture of gases, where the total pressure is 1.50 atm, is 300. torr. What is the mole fraction
makvit [3.9K]

Answer:

The mole fraction of N₂ is 0.26.

Explanation:

The pressure exerted by a particular gas in a mixture is known as its partial pressure. So, Dalton's law states that the total pressure of a gas mixture is equal to the sum of the pressures that each gas would exert if it were alone:

PT = PA + PB

This relationship is due to the assumption that there are no attractive forces between the gases.

Dalton's partial pressure law can also be expressed in terms of the mole fraction of the gas in the mixture. The mole fraction is a dimensionless quantity that expresses the ratio of the number of moles of a component to the number of moles of all the components present.

So in a mixture of two or more gases, the partial pressure of gas A can be expressed as:

PA = XA * PT

In this case:

  • PA= PN₂= 300 torr
  • XA=XN₂= ?
  • PT= 1.50 atm= 1140 torr (being 1 atm= 760 torr)

Replacing:

300 torr= XN₂*1140 torr

Solving:

X_{N_{2} } =\frac{300 torr}{1140 torr}

XN₂= 0.26

<u><em>The mole fraction of N₂ is 0.26.</em></u>

6 0
3 years ago
When 240 mg of a certain molecular compound X are dissolved in 35.0 g of dibenzyl ether ((C6H5CH2)2O), the freezing point of the
DedPeter [7]

Answer: MM = 16.55 g/mol

Explanation: <u>Freezing</u> <u>point</u> <u>depression</u> is a phenomena that explains why adding a solute to a solvent decreases the solvent freezing point: when a substance begins to freeze, its molecules slows down and rearrange itself forming a solid. If a solute is added, the molecules from the solvent interfere in the formation of the solid. To guarantee the transformation, the solution has to cooled down even more.

Freezing point and molality concentration is related by

\Delta T=T_{f}_{(solvent)}-T_{f}_{(solution)}=K_{f}.m

where

ΔT is freezing point depression

T_{f}_{(solvent)} and T_{f}_{(solution)} are freezing point of solvent and solution, respectively

K_{f} is freezing point depression constant

m is molality concentration

<u />

Dibenzyl ether is the solvent and has the following properties: K_{f}= 6.27 and T_{f} = 3.6°C.

Molality concentration is

m=\frac{T_{(solvent)}-T_{(solution)}}{K_{f}}

m=\frac{3.6-1}{6.27}

m = 0.415

<u>Molality</u> <u>concentration</u> is moles (n) of solute dissolved in a mass, in kilogram, of solvent.

m=\frac{moles}{mass(kg)}

n = m(mass of solvent in kg)

n = 0.415(0.035)

n = 0.0145

<u>Molar</u> <u>mass</u> (M) is the weight of one sample mole and can be calculated as

n=\frac{m}{M}

M = \frac{m}{n}

m in grams

Molar mass of compound X is

M=\frac{0.24}{0.0145}

M = 16.55

<u>Molar mass of molecular</u><u> compound X is 16.55g/mol</u>

3 0
3 years ago
Na+ leaks through neuron membranes faster than k+ because of the properties of the non-gated leak channels. na+ leaks through ne
Pavlova-9 [17]

Answer: b. False

K+ ions move faster than the Na+ ions through the neuron membranes.

The concentration of Sodium ions outside the cell is very high. The concentration of Potassium ions inside the cells is very high. Leakage channels thus allow sodium ions to move inside the cells and pumps out the Potassium from the cells.

5 0
3 years ago
Which heats up the fastest? treated glass, aluminum, stainless steel, or copper?
GrogVix [38]

Answer:

stainless steel

Explanation:

stainless steel would heat up fast because it is made of metal

8 0
3 years ago
How many kilograms of dry air are in a room that measures 15.0 ft by 18.0 ft by 8.00 ft? Use the density of air of 1.168 g/L. Th
Nady [450]

Answer:

0.0481 kg.

Explanation:

First, we need to find the volume of the room.

15 x 18 x 8 = 1350

The volume of the room is 1350 ft³

Now, we convert feet to centimeters

1350 x 30.48 = 41,148

The volume is 41,148 cm³

1 cm³ = 1 mL

So we can say that the volume of the room is also 41,148 mL

Then, we convert milliliters to liters

41,148 ÷ 1,000 = 41.148

There are 41.148 liters of air in the room

We multiply the air's density with volume in liters

41.148 x 1.168 = 48.060864

There are 48.060864 grams of air in the room

Finally, convert grams to kilograms

48.060864 ÷ 1,000 = 0.048060864

0.048060864 kilograms of air are in the room.

4 0
3 years ago
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