Find the molality of a solution of 58.5 g NaCl dissolved in 0.556 kg of water

What is the concentration of a solution containing 1.11 g sugar (sucrose, C12H22O11, MW = 342.3 g/mol, d = 1.587 g/cm3) in 432 m

djyliett [7]

Answer:

0.0075 M

0.0060 m

Explanation:

Our strategy here is to use the definition of molarity and molality to solve this question.

The molarity is the number of moles of solute, sucrose in this case, per liter of solution.

The molality is the number of moles of solute per kilogram of solvent.

So the molarity of the solution is

M = moles of solute/ V solution

As we see we need the volume of solution since we are only given the volume of solvent, but this will be easy to compute since we have the density of sucrose.

So determine the moles of sucrose , and the volume of solution:

Moles sucrose = 1.11 g/342.3 g/mol = 3.24 x 10⁻³ M

Volume of solution = Vol Sucrose + Vol glycerine

d = m/V ⇒ Vsucrose = m / d = 1.11 g/ 1.587 g/cm³ = 0.70 cm³

Vol solution = 432 mL + 0.70 mL = 432.7 mL (1cm³ = 1 mL)

Vol solution = 432.7 mL x 1 L / 1000 mL = 0.4327 L

⇒ M = 3.2 x 10⁻³ mol / 0.4327 L = 0.0075 M

For the molarity what we need is to first calculate the kilograms of glycerine from the given density:

d = m/v ⇒ m = d x v = 1.261 g/cm³ x 432 cm³ = 544.75 g

Converting to Kg:

544.75 g x 1 Kg/ 1000 g = 0.544 kg

Now the molality is

m = mol sucrose/ kg solvent = 3.24 x 10⁻³ mol / 0.544 Kg = 0.0060 m

Note: In the calculation for volume of solution we could have approximated it to that of just glycerine, but since the density of sucrose was given we calculated the total volume of solution to be more rigorous.

8 0

3 years ago

A sample of oxide iron weighing 2.40g was heated in a stream of hydrogen until it was completely converted to the metal. If the

wlad13 [49]

Answer:

Fe₂O₃

Explanation:

To solve this question we must find the moles of Iron in 1.68g. With the difference of the masses we can find the moles of oxygen. The formula will be obtained with the ratio of both amount of moles:

<em>Moles Fe:</em>

1.68g * (1mol / 56g) =0.03moles

<em>Moles O:</em>

2.40g-1.68g = 0.72g * (1mol/16g) = 0.045moles

The ratio O/Fe is:

0.045moles / 0.03moles = 1.5 moles. this ratio is obtained if the formula is:

4 0

3 years ago

Changes to the global climate could include _______.

frosja888 [35]

1. Answer is d. all of the above.

Climate can be defined as the data collection of weather conditions of a long period of time in a certain area. The weather conditions that affect to the climate are temperature, precipitation, atmospheric pressure, wind and so on. Any changes in weather can change the global climate.

2. Answer is c. ozone.

Trees release oxygen and water vapor into the atmosphere but not ozone. The oxygen gas is released by trees as the by-product of photosynthesis. This is the natural way of production of oxygen gas. Water vapor can be released due to the transpiration of trees.

6 0

4 years ago

Read 2 more answers

When barium reacts with tellurium to form an ionic compound, each metal atom loses electron(s) and each nonmetal atom gains elec

Bess [88]

<u>Answer:</u> The ionic compound formed is $baF_2$ (barium fluoride)

<u>Explanation:</u>

Ionic compound is formed by the complete transfer of electrons from 1 atom to another atom. The cation is formed by the loss of electrons by metals and anions are formed by gain of electrons by non metals.

Taking the metal as barium and non-metal as fluorine.

Barium is the 56th element of the periodic table having electronic configuration of $[Xe]6s^2$

This element will loose 2 electrons and will form $Ba^{2+}$ ion

Fluorine is the 9th element of the periodic table having electronic configuration of $[He]2s^22p^5$

This element will gain 1 electron and will form $F^{-}$ ion

By criss-cross method, the oxidation state of the ions gets exchanged and they form the subscripts of the other ions. This results in the formation of a neutral compound.

Hence, the ionic compound formed is $baF_2$ (barium fluoride)

7 0

3 years ago

Which are possible solutions to air pollution?select all that apply

Ksenya-84 [330]

Develop cost efficient methods to use solar energy
increase the use of wind power
reduce the use of coal and oil

6 0

3 years ago