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Natali5045456 [20]
3 years ago
5

A solution is prepared by dissolving 20.1 g of MgCl2 with the addition of 157.0 mL of water (density of water is 1.00g/cm3). The

density of the resulting solution was determined to be 1.089g/cm3. Calculate the molar concentration of this solution: Hint: Make sure you understand the definition on Molar concentration
Chemistry
1 answer:
Nezavi [6.7K]3 years ago
6 0

Answer:

1.3 M.

Explanation:

  • We need to calculate the mass of the solution:

mass of the solution = mass of MgCl₂ + mass of water

mass of MgCl₂ = 20.1 g.

mass of water = d.V = (157.0 mL)(1.0 g/cm³) = 157.0 g.

∴ mass of the solution = mass of MgCl₂ + mass of water = 20.1 g + 157.0 g = 177.1 g.

  • Now, we can get the volume of the solution:

V of the solution = (mass of the solution)/(density of the solution) = (177.1 g)/(1.089 g/cm³) = 162.62 mL = 0.163 L.

Molarity is the no. of moles of solute dissolved in a 1.0 L of the solution.

M = (no. of moles of MgCl₂) / (Volume of the solution (L)).

<em>∴ M = (mass/molar mass)of MgCl₂ / (Volume of the solution (L)) =</em> (20.1 g/95.211 g/mol) / (0.163 L) = <em>1.29 M ≅ 1.3 M.</em>

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Iron(II) sulfate, an iron supplement , FeSO4 Express your answer to four significant figures and include the appropriate units.
strojnjashka [21]

Answer:

Molar mass = 151.9 g/mol

Explanation:

The molar mass of a compound is obtained by adding u the individual atomic masses in the compound. The unit is g/mol.

In FeSO4, we have one Fe, one S and 4 O.

The atomic masses are given as follows;

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In four significant figures;

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5 0
3 years ago
Nitrogen gas reacts with hydrogen gas to produce ammonia. How many liters of hydrogen gas at 95kPa and 15∘C are required to prod
viktelen [127]

Answer:

222.30 L

Explanation:

We'll begin by calculating the number of mole in 100 g of ammonia (NH₃). This can be obtained as follow:

Mass of NH₃ = 100 g

Molar mass of NH₃ = 14 + (3×1)

= 14 + 3

= 17 g/mol

Mole of NH₃ =?

Mole = mass /molar mass

Mole of NH₃ = 100 / 17

Mole of NH₃ = 5.88 moles

Next, we shall determine the number of mole of Hydrogen needed to produce 5.88 moles of NH₃. This can be obtained as follow:

N₂ + 3H₂ —> 2NH₃

From the balanced equation above,

3 moles of H₂ reacted to produce 2 moles NH₃.

Therefore, Xmol of H₂ is required to p 5.88 moles of NH₃ i.e

Xmol of H₂ = (3 × 5.88)/2

Xmol of H₂ = 8.82 moles

Finally, we shall determine the volume (in litre) of Hydrogen needed to produce 100 g (i.e 5.88 moles) of NH₃. This can be obtained as follow:

Pressure (P) = 95 KPa

Temperature (T) = 15 °C = 15 + 273 = 288 K

Number of mole of H₂ (n) = 8.82 moles

Gas constant (R) = 8.314 KPa.L/Kmol

Volume (V) =?

PV = nRT

95 × V = 8.82 × 8.314 × 288

95 × V = 21118.89024

Divide both side by 95

V = 21118.89024 / 95

V = 222.30 L

Thus the volume of Hydrogen needed for the reaction is 222.30 L

8 0
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HELP PLEASE I HAVE A TEST TODAY AND I DON'T UNDERSTAND ANY OF THIS...
myrzilka [38]

Answer:

About 67 grams or 67.39 grams

Explanation:

First you would have to remember a few things:

 enthalpy to melt ice is called enthalpy of fusion.  this value is 6.02kJ/mol

  of ice  

 it takes 4.18 joules to raise 1 gram of liquid water 1 degree C

 water boils at 100 degrees C and water melts above 0 degrees C

 1 kilojoules is 1000 joules

  water's enthalpy of vaporization (steam) is 40.68 kJ/mol

  a mole of water is 18.02 grams

  we also have to assume the ice is at 0 degrees C

Step 1

Now start with your ice.  The enthalpy of fusion for ice is calculated with this formula:

q = n x ΔH    q= energy, n = moles of water, ΔH=enthalpy of fusion

Calculate how many moles of ice you have:

150g x (1 mol / 18.02 g) = 8.32 moles

Put that into the equation:

q = 8.32 mol x 6.02 = 50.09 kJ of energy to melt 150g of ice

Step 2

To raise 1 gram of water to the boiling point, it would take 4.18 joules times 100 (degrees C)  or 418 joules.

So if it takes 418 joules for just 1 gram of water, it would take 150 times that amount to raise 150g to 100 degrees C.  418 x 150 = 62,700 joules or 62.7 kilojoules.

So far you have already used 50.09 kJ to melt the ice and another 62.7 kJ to bring the water to boiling.  That's a total of 112.79 kJ.

Step 3

The final step is to see how much energy is left to vaporize the water.

Subtract the energy you used so far from what you were told you have.

265 kJ - 112.79 kJ = 152.21 kJ

Again q = mol x ΔH (vaporization)

You know you only have 152.21 kJ left so find out how many moles that will vaporize.

152.21 kJ = mol x 40.68  or   mol = 152.21 / 40.68  = 3.74 moles

This tells you that you have vaporized 3.74 moles with the energy you have left.

Convert that back to grams.

3.74 mol   x  ( 18.02 g / 1 mol ) = 67.39 grams

5 0
2 years ago
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