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raketka [301]
3 years ago
10

When 6.13 g of a certain molecular compound X are dissolved in 90. g of formamide (NH2COH), the freezing point of the solution i

s measured to be 2.1 °C. Calculate the molar mass of X. If you need any additional information on formamide, use only what you find in the ALEKS Data resource. Also, be sure your answer has a unit symbol, and is rounded to the correct number of significant digits.
Chemistry
1 answer:
belka [17]3 years ago
8 0

Answer:

321.6 g/Mol

Explanation:

mass of solvent in kilograms = 90g/1000 = 0.09 Kg

Given that;

ΔTf = Kf . m . i

Where;

Kf = freezing point constant = 4.25 °C/Kg mol

m = molality of the solution

i = Van't Hoff factor = 1 (since the substance is molecular)

ΔTf = freezing point of pure solvent - freezing point of solution

freezing point of pure solvent = 3 °C

ΔTf = 3 °C - 2.1 °C

ΔTf = 0.9  °C

0.9= 4.25 * 6.13/M/0.09 * 1

0.9= 26.0525/M * 1/0.09

0.9 = 26.0525/0.09 M

0.9 * 0.09M = 26.0525

M = 26.0525/0.9 * 0.09

M= 321.6 g/Mol

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prohojiy [21]

Explanation:

A point of temperature at which both solid and liquid state of a substance remains in equilibrium without any change in temperature then this temperature is known as melting point.

For example, melting point of water is 0 ^{o}C. So, at this temperature solid state of water and liquid state are present in equilibrium with each other.

Therefore, when a 100 g of given pure metal in solid state is heated at its exact melting point which is 215^{o}C then some of the solid will change into liquid state but the temperature will remains the same.  

4 0
3 years ago
Determine how many liters of hydrogen adjusted to STP there are in a 50.0 liter steel cylinder if the pressure inside is 100.0 a
Dvinal [7]

Answer : The volume of hydrogen gas at STP is 4550 L.

Explanation :

Combined gas law is the combination of Boyle's law, Charles's law and Gay-Lussac's law.

The combined gas equation is,

\frac{P_1V_1}{T_1}=\frac{P_2V_2}{T_2}

where,

P_1 = initial pressure of gas = 100.0 atm

P_2 = final pressure of gas at STP = 1 atm

V_1 = initial volume of gas = 50.0 L

V_2 = final volume of gas at STP = ?

T_1 = initial temperature of gas = 27.0^oC=273+27.0=300K

T_2 = final temperature of gas at STP = 0^oC=273+0=273K

Now put all the given values in the above equation, we get:

\frac{100.0atm\times 50.0L}{300K}=\frac{1atm\times V_2}{273K}

V_2=4550L

Therefore, the volume of hydrogen gas at STP is 4550 L.

3 0
3 years ago
A 118-ml flask is evacuated and found to have a mass of 97.129 g. when the flask is filled with 768 torr of helium gas at 35 ?c,
Inessa05 [86]
The full question asks to decide whether the gas was a specific gas. That part is missing in your question. You need to decide whether the gas in the flask is pure helium.

To decide it you can find the molar mass of the gas in the flask, using the ideal gas equation pV = nRT, and then compare with the molar mass of the He.

From pV = nRT you can find n, after that using the mass of gass in the flask you use MM = mass/moles.

1) From pV = nRT, n = pV / RT

Data:
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R = 0.082 atm*liter/mol*K
p = 768 torr * 1 atm / 760 torr = 1.0105 atm
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n = 1.015 atm * 0.118 liter / [ 0.082 atm*liter/K*mol  * 308.15K] =0.00472 mol

mass of gas = mass of the fask with the gas - mass of the flasl evacuated = 97.171 g - 97.129 g = 0.042

=> MM =  mass/n = 0.042 / 0.00472 = 8.90 g/mol

Now from a periodic table or a table you get that the molar mass of He is 4g/mol

So the numbers say that this gas is not pure helium , because its molar mass is more than double of the molar mass of helium gas.
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hram777 [196]

Answer:

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VladimirAG [237]
Two elements that have similar properties has silicon would be above or below silicon. they are germanium or antimony. 
   
6 0
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