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svet-max [94.6K]
3 years ago
11

What is the molality of an aqueous kbr solution with a mole fraction of kbr, x, equal to 0.245?

Chemistry
1 answer:
kompoz [17]3 years ago
4 0
Molality is used to express concentration and it is:
molality = moles of solvent / kilogram solution

Now, lets assume there is one mole of solution. Then, there will be 0.245 moles of KBr and 0.755 moles of water. We multiply these molar fractions with the substances' molar masses to find the weight of one mole of solution.

Weight of one mole of solution = 0.245 * 119 + 0.755 * 18
Weight = 42.74 grams

Converting this weight to kilograms, this is 0.043 kg. We now multiply the moles of KBr by the kilograms of solution to find the molality:

molality = 0.245 / 0.043

The molality of the solution is 5.70 moles per kg
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How much ch2o is needed to prepare 445 ml of a 2.65 m solution of ch2o?
worty [1.4K]

Answer: 35.4 grams

Explanation:

Molarity of a solution is defined as the number of moles of solute dissolved per Liter of the solution.

Molarity=\frac{n\times 1000}{V_s}

where,

Molality = 2.65

n= moles of solute =?

 V_s = volume of solution in ml = 445 ml

Putting in the values we get:

2.65=\frac{n\times 1000}{445ml}

n=1.18

Mass of solute in g=moles\times {\text {molar mass}}=1.18mol\times 30.02g/mol=35.4g

Thus 35.4 grams of CH_2O is needed to prepare 445 ml of a 2.65 m solution of CH_2O.

8 0
3 years ago
In what direction does energy move​
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In every direction guyz but conventionally it moves from higher potential to lower potential

7 0
2 years ago
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Calculate the number of moles of an ideal gas if it occupies 1750 dm3 under 125,000 pa at a temperature of 127 c. a. 0.21 moles
labwork [276]

The number of mole will be 65.81 mole.

An ideal gas would be one for which both the overall volume of the molecules and even the forces that exist between them are so negligible as to have no influence on the behavior of something like the gas.

Number of ideal gas can be calculated by using the formula:

PV = nRT

where, p is pressure, n is number of mole, R is gas constant and T is temperature.

Given data:

V= 1750 dm^{3} = 1750 L

P = 125,000 p = 1.2 atm

R = 0.082 L /mole kelvin

T = 273+127 = 400 K

Now, put the value of given data in above equation.

1.23atm x 1750L = n x 0.0820atm x Liter/ mole x kelvin  x 400K

n = 65.81 mole.

Therefore, the number of mole will be 65.81 mole

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brainly.com/question/21050624

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6 0
2 years ago
Select the ion.<br><br>1)Cu<br>2)PO4-3<br>3)SO2
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I believe the answer is B. PO4-3
6 0
4 years ago
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A molecule contains five atoms and has a molecular weight of 85 g per mole. the atoms are of elements with atomic numbers 1, 6,
inessss [21]

Answer:

            Dichloromethane

Explanation:

As we know the atomic number given belongs to following elements, i.e.

Atomic #                   Element                      M.Mass

   1                           Hydrogen                    1 g.mol⁻¹

   6                          Carbon                        12 g.mol⁻¹

   17                         Chlorine                      35.5 g.mol⁻¹

Also the molecular formula of Dichloromethane is,

                           =  CH₂Cl₂

Putting molar masses of each element,

                          =  (12)₁  +  (1)₂  +  (35.5)₂

                          =  12  +  2  +  71

                          =  85 g.mol⁺¹

Result:

         Hence the only possible structure containing 5 atoms is Dichloromethane.

6 0
4 years ago
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