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2 years ago

How many formula units are in 25.4 g of MgCl2?

Chemistry

1 answer:

stiv31 [10]2 years ago

5 0

Answer: 1.58 x $10^{23}$

Explanation:

1 mole of magnesium chloride has a mass of 95.211 g and contains 6.022⋅ $10^{23}$ formula units of magnesium chloride, you can say that,

25.0 g x (6.022 x $10^{23}$ form units MgCl2) /95.211 = 1.58 x $10^{23}$

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I really need help pls, will pay anything

Triss [41]

Explanation:

For the first part,

Reaction equation:

N₂ + 3H₂ → 2NH₃

Given:

Number of moles of NH₃ = 6 moles

Unknown:

Number of moles of N₂ = ?

Solution:

N₂ + 3H₂ → 2NH₃;

From the reaction above, we solve from the known specie to the unknown. Ensure that the equation is balanced;

2 moles of NH₃ is produced from 1 mole of N₂

6 moles of NH₃ will be produced from $\frac{6}{2}$ mole of N₂

= 3moles of N₂

The number of moles of N₂ is 3 moles

ii.

Given parameters:

Number of moles of sulfur = 2.4moles

Molar mass of sulfur = 32.07g/mol

Unknown:

Mass of sulfur = ?

Solution:

The number of moles of any substance can be found using the expression below;

Number of moles = $\frac{mass}{molar mass}$

Mass of sulfur = number of moles of sulfur x molar mass

Insert the parameters and solve;

Mass of sulfur = 2.4 x 32.07 = 76.97g

6 0

2 years ago

Calculate the molar concentration of the Cl⁻ ions in 0.65 M CaCl2(aq), assuming that the dissolved substance dissociates complet

alexandr1967 [171]

The question here is solved using basic chemistry. CaCl2(aq) is an ionic compound which will have the releasing of 2 Cl⁻ ions ions in water for every molecule of CaCl2 that dissolves.
CaCl2(s) --> Ca+(aq) + 2 Cl⁻(aq)
[Cl⁻] = 0.65 mol CaCl2/1L × 2 mol Cl⁻ / 1 mol CaCl2 = 1.3 M
The answer to this question is [Cl⁻] = 1.3 M

5 0

3 years ago

A cubic container is filled up with an unknown liquid whose density is 0.180 g/cm3. The side lengh of the container is 5.00cm. W

Oksi-84 [34.3K]

Answer:

THE MASS OF THE LIQUID IS 22.5 g

Explanation:

Density = 0.180 g/cm3

Side length = 5 cm

Mass = unknown

To calculate the mass of the liquid, we use the formula:

Mass = density * volume

Volume of a cube or cuboid container = l^3

Volume = 5 ^3 = 125 cm3

So therefore, the mass of the liquid is:

Mass = 0.180 * 125

Mass = 22.5 g

In conclusion, the mass of the liquid in the container is 22.5 g

4 0

2 years ago

Given that the formula for mass percent is mass % = mass solutemass solution100%, what will be our starting assumption when conv

attashe74 [19]

Answer:

1. The starting assumption is an amount of 100 grams of solution.

2. It simplifies the problem, because the percentage tells directly the mass of solute present in 100 grams of solution and from that point the calculations are easy to do.

Explanation:

Percentages are always based on the amount of total substance, total solution if it is the case.

If it is mass percentage the amount of total substance is mass.

For instance, a 30% mass solution of sodium chloride means 30 grams of sodium chloride (solute) in 100 grams of solution (includes the solvent plus the solute).

mass percent is mass % = (mass solute / mass solution) × 100%,

Molarity is number of moles of solute per volume in liters of solution:

Molarity = (moles solute / liters solution)

In this case, to convert from percentage to molarity you start assuming a base of 100 grams of solution. For the example of the 30% sodium chloride solution, by assuming 100 grams of solution, you had 30 grams of solute, which you can convert into moles, and, by using the density of the solution (which you need to know), you convert the 100 grams of solution into volume (in liters). Then, you can divide the number of moles of solute into the number of liters of solution, having started with the assumption of 100 grams of solution.

Molality is the number of moles of solute per kilograms of solvent.

Molality = moles solute / kg of solvent.

Again, to convert from percentage to molality, your first step is to assume a base of 100 grams of solution. Then, for the same example of 30% sodium chloride, convert 30 grams of solute to moles, and the 100 grams of solution into 70 grams of solvent (100g solution - 30 grams solute = 70 grams solvent), which is 0.070 kg. Finally, divide the moles of solute by 0.070 kg of solvent.

Then, assuming the amount of solution equal to 100 grams simplifies the problem because the percentage tells directly the amount of solute, which you can convert into moles making calculations easier than with other amount of solution.

5 0

2 years ago

How do I balance the chemical equation Ca(s) +O2(g) =CaO(s)

Sever21 [200]

Hey there!

Ca + O₂ → CaO

Balance O.

2 on the left, 1 on the right. Add a coefficient of 2 in front of CaO.

Ca + O₂ → 2CaO

Balance Ca.

1 on the left, 2 on the right. Add a coefficient of 2 in front of Ca.

2Ca + O₂ → 2CaO

Our final balanced equation: 2Ca + O₂ → 2CaO

Hope this helps!

7 0

2 years ago

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