A solution is made by dissolving 14.57 g of sodium bromide (NaBr) in
415 g of water.
What is the molality of the solution?
[?] m NaBr
Molar mass of NaBr: 102.89 g/mol

0.342 m

Explanation:

From the question given above, the following data were obtained:

Mass of NaBr = 14.57 g

Mass of water = 415 g

Molar mass of NaBr = 102.89 g/mol

Molality of NaBr =?

Next, we shall determine the number of mole in 14.57 g of NaBr. This can be obtained as follow:

Mass of NaBr = 14.57 g

Molar mass of NaBr = 102.89 g/mol

Mole of NaBr =?

Mole = mass / molar mass

Mole of NaBr = 14.57 / 102.89

Mole of NaBr = 0.142 mole

Next, we shall convert 415 g of water to kg. This can be obtained as follow:

1000 g = 1 Kg

Therefore,

415 g = 415 g × 1 Kg / 1000 g

415 g = 0.415 Kg

Thus, 415 g is equivalent to 0.415 Kg.

Finally, we shall determine Molality of the solution as follow:

Mole of NaBr = 0.142 mole

Mass of water = 0.415 Kg

Molality of NaBr =?

Molality = mole / mass of water in Kg

Molality of NaBr = 0.142 / 0.415

Molality of NaBr = 0.342 m

Therefore, the molality of NaBr solution is 0.342 m.

"you start with 15.67 g mgco3-xh2o, when heated and all the water is removed, you are left with 7.58 g mgco3 only.

therefore, you had 15.67 - 7.58 = 8.09g h2o  

moles of each :

7.58g mgco3 = ? moles = 7.58g / 83.4g/mole = 0.09moles  

8 09g h2o = ? moles = 8.09g / 18g/mole = 0.44moles  

molar ratio between the two by dividing both numbers by the smallest number :

0.09 / 0.09 = 1  

0.44 / 0.09 = 4.8  

mgco3-5h2o"

the best answer is d because the strong cohesion is caused by the ability of water molecules to undergo hydrogen bonding.

a is incorrect because when water solidifies, it becomes   ice, which expands and occupies a bigger volume for the same mass of water in its liquid state.

b is incorrect because water has high surface tension. besides bonding to itself it hydrogen bonds to other molecules at the top decreasing possibility for breaking of attractive forces.

c is incorrect because the water molecule has oxygen which is highly electronegative and so pulls the electron pair towards itself creating a dipole moment, making the molecule polar.

e is incorrect because water has strong adhesion, ability to stick to other molecules such as glass because of this molecules having stronger hydrogen bonding than water.