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2 years ago

How many atoms of Ca are present in 80.156 grams of Ca?

Chemistry

1 answer:

cricket20 [7]2 years ago

5 0

Answer:

1.2044 x 10²⁴ atoms.

Explanation:

We need to calculate the no. of moles of Ca that are present in 80.156 g using the relation:

n = mass/atomic mass = (80.156 g)/(40.078 g/mol) = 2.0 mol.

It is known that every 1.0 mole of a molecule contains Avogadro's number of molecules (NA = 6.022 x 10²³).

Using cross multiplication:

1.0 mole of Ca contains → 6.022 x 10²³ atoms.

2.0 moles of Ca contains → ??? atoms.

∴ 2.0 mole of (80.156 g) Ca contain = (2.0 mol)(6.022 x 10²³) = 1.2044 x 10²⁴ atoms.

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When an athlete gets hurt they apply sometimes an instant cold pack to the injury. The instant cold pack works by mixing two che

NeX [460]

Answer:

The evidence showing that there is a chemical reaction taking place is the instantaneous temperature drop once the cold pack is shaken.

Explanation:

When an athlete applies a cold pack to the injury, they shake it before, mixing the water and ammonium-nitrate fertilizer inside the cold pack. This mixing is an endothermic reaction, which means it absorbs heat. In turn, the temperature falls to 35 F for around 10 minutes.

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2 years ago

What would have happened to your results if during the dehydration some of the copper (ii) sulfate splatter out of the crucible-

lidiya [134]

Answer : The results would show more amount of water in the hydrated sample.

Explanation :

The amount of water of crystallization can be found by taking the masses of hydrated copper sulfate and anhydrous copper sulfate.

The difference in masses indicates the mass of water lost during dehydration process.

If during dehydration process, some of the copper sulfate spatters out of the crucible, then this would give us less mass for anhydrous sample than the actual.

As a result, the difference in masses of hydrated sample and the anhydrous sample would be more.

Therefore the results would show more amount of water in the hydrated sample.

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2 years ago

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likoan [24]

Answer:

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Explanation:

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2 years ago

Valproic acid, used to treat seizures and bipolar disorder, is composed of C, H, and O. A 0.165-g sample is combusted to produce

sergeinik [125]

Answer:

The empirical formula is = $C_4H_8O$

The formula of Valproic acid = $C_8H_{16}O_2$

Explanation:

Mass of water obtained = 0.166 g

Molar mass of water = 18 g/mol

Moles of $H_2O$ = 0.166 g /18 g/mol = 0.00922 moles

2 moles of hydrogen atoms are present in 1 mole of water. So,

Moles of H = 2 x 0.00922 = 0.01844 moles

Molar mass of H atom = 1.008 g/mol

Mass of H in molecule = 0.01844 x 1.008 = 0.018588 g

Mass of carbon dioxide obtained = 0.403 g

Molar mass of carbon dioxide = 44.01 g/mol

Moles of $CO_2$ = 0.403 g /44.01 g/mol = 0.009157 moles

1 mole of carbon atoms are present in 1 mole of carbon dioxide. So,

Moles of C = 0.009157 moles

Molar mass of C atom = 12.0107 g/mol

Mass of C in molecule = 0.009157 x 12.0107 = 0.11 g

Given that the Valproic acid only contains hydrogen, oxygen and carbon. So,

Mass of O in the sample = Total mass - Mass of C - Mass of H

Mass of the sample = 0.165 g

Mass of O in sample = 0.165 - 0.11 - 0.018588 = 0.036412 g

Molar mass of O = 15.999 g/mol

Moles of O = 0.036412 / 15.999 = 0.002276 moles

Taking the simplest ratio for H, O and C as:

0.01844 : 0.002276 : 0.009157

= 8 : 1 : 4

The empirical formula is = $C_4H_8O$

Molecular formulas is the actual number of atoms of each element in the compound while empirical formulas is the simplest or reduced ratio of the elements in the compound.

Thus,

Molecular mass = n × Empirical mass

Where, n is any positive number from 1, 2, 3...

Mass from the Empirical formula = 4×12 + 8×1 + 16= 72 g/mol

Molar mass = 144 g/mol

So,

Molecular mass = n × Empirical mass

144 = n × 72

⇒ n = 2

The formula of Valproic acid = $C_8H_{16}O_2$

7 0

2 years ago

What is the symbol for the isotope of 58 co that possesses 33 neutrons?

Leona [35]

Element with an atomic number of 58 is actually Cerium, so the symbol should be Ce, not Co because that is Cobalt which has an atomic number of 27. With that being said, the notation for isotopes is the symbol of the element with a superscript and a subscript that are aligned. The superscript represents the mass number.

Mass number = protons + neutrons = 58 + 33 = 91

The subscript is the atomic number which is 58. The notation is written in the picture attached.

6 0

2 years ago

Read 2 more answers