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2 years ago

Find the mass of calcium oxide produced from the thermal decomposition of 50 g of calcium carbonate.

Chemistry

1 answer:

anastassius [24]2 years ago

3 0

Answer:

28 g

Explanation:

The chemical equation of the reaction is given below:

CaCO₃ (s) ⇒ CaO (s) + O₂ (g)

From the chemical equation, 1 mole of CaCO₃ produces 1 mole of CaO.

So, we find the number of moles,n of CaCO₃ in 50 g from

n = m/M where n = number of moles of CaCO₃, m = mass of CaCO₃ and M = molar mass of CaCO₃ = 40 g/mol + 12 g/mol + 3 × 16 g/mol = 52 g/mol + 48 g/mol = 100 g/mol

So, n = m/M

= 50 g/100 g/mol

= 0.5 mol

Since From the chemical equation, 1 mole of CaCO₃ produces 1 mole of CaO, then 0.5 × 1 mole of CaCO₃ produces 0.5 × 1 mole of CaO, which is 0.5 mole of CaCO₃ produces 0.5 mole of CaO.

So, we have 0.5 mol of CaO.

We find the mass of CaO from

n =m'/M' where n = number of moles of CaO = 0.5, m' = mass of CaO and M' = molar mass of CaO = 40 g/mol + 16 g/mol = 56 g/mol

So, m' = nM'

= 0.5 mol × 56 g/mol

= 28 g

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Sonbull [250]

Answer:

A is an endothermic reaction.

Explanation:

When energy of breaking bonds is greater than the energy released during making of bonds, we need to supply energy to the reaction and thus the reaction is called as endothermic reaction. We can also say that the enthalpy of formation of products is more than the enthalpy of formation of reactants making overall enthalpy change to be positive.

While in case B, the energy to break bond is less than the energy released during making of bonds. thus there is overall released of energy during the reaction and hence it is exothermic reaction.

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3 years ago

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An atom of argon rarely bonds to an atom of another element because an argon atom has

Solnce55 [7]

The answer is (1) 8 valence electrons. Argon, being a noble gas, already possesses a full octet of valence electrons and is, therefore, very, very stable. It has an almost indomitable tendency to retain that octet. That is why it so rarely participates in any sort of bonding.

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3 years ago

A chemist must prepare of potassium hydroxide solution with a pH of at . He will do this in three steps: Fill a volumetric flask

maksim [4K]

The question is incomplete; the complete question is:

A chemist must prepare 800.0mL of potassium hydroxide solution with a pH of 13.00 at 25 degree C. He will do this in three steps: Fill a 800.0mL volumetric flask about halfway with distilled water. Weigh out a small amount of solid potassium hydroxide and add it to the flask. Fill the flask to the mark with distilled water. Calculate the mass of potassium hydroxide that the chemist must weigh out in the second step. Round your answer to 2 significant digits.

Answer:

4.5g (to 2 significant digits)

Explanation:

Now we must remember that KOH is a strong base, therefore it will practically dissociate completely.

To find the pH we can use the equation pH + pOH = 14.

Firstly to find the pOH:

13.00 + pOH = 14

pOH = 1.00

To find the [OH-]

Since

pOH= -log[OH^-]

[OH^-] = antilog (-pOH)

[OH^-]= antilog (-1)

[OH^-] = 0.1 molL-1

Since we've established that KOH is a strong base, we know that [OH-] = [KOH]

Also, we know that concentration = number of moles/volume

we have the concentration and the volume now so we can calculate the number of number of moles as follows:

The 800mL volume is the same as 0.8L

0.1 molL-1= number of moles/0.8L

0.08 moles = number of moles

now we can calculate the amount of solid KOH required

the molar mass of KOH = 39 + 16 +1 = 56 gmol-1

56 x 0.08 moles = 4.48g

So in 800mL of pH 13.00 KOH there is 4.5g of KOH dissolved.

3 0

3 years ago

Which one of the following substances would be the most soluble in CCl4?

maria [59]

Answer: Option (d) is the correct answer.

Explanation:

Carbon tetrachloride $(CCl_{4})$ is a non-polar solvent. Whereas out of the given options, $Na_{2}SO_{4}$ , $H_{2}O$ , $CH_{3}CH_{2}CH_{2}CH_{2}OH$ , and HI are all polar molecules.