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Dafna11 [192]
3 years ago
13

How many molecules of Ca are found in a sample with 0.2 mols?

Chemistry
1 answer:
DochEvi [55]3 years ago
6 0

Answer:

\boxed{1.2 \times 10^{23}\text{ atoms}}

Explanation:

6.023 × 10²³ atoms of Ca are in 1 mol of Ca

\text{No. of atoms} = \text{0.2 mol} \times \dfrac{6.023 \times 10^{23}\text{atoms }}{\text{1 mol }} = \mathbf{1.2 \times 10^{23}} \textbf{ atoms}}\\\\\text{There are }\boxed{\mathbf{1.2 \times 10^{23}} \textbf{ atoms}} \text{ atoms in 0.20 mol of Ca}

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what is the concentration in ppm of a solution which is prepared by dissolving in 15mg of nacl in 200ml water
bezimeni [28]

Answer:

Explanation:

In weight/volume (w/v) terms,

   1 ppm = 1g m-3 = 1 mg L-1 = 1 μg mL-1

200 mL = 0.2 L

15 / 0.2 mg L-1 =75 ppm

6 0
3 years ago
How much time would it take for 336 mg of copper to be plated at a current of 5.6 A ? Express your answer using two significant
schepotkina [342]

Answer:

1.8 × 10² s

Explanation:

Let's consider the reduction that occurs upon the electroplating of copper.

Cu²⁺(aq) + 2 e⁻ ⇒ Cu(s)

We will establish the following relationships:

  • 1 g = 1,000 mg
  • The molar mass of Cu is 63.55 g/mol
  • When 1 mole of Cu is deposited, 2 moles of electrons circulate.
  • The charge of 1 mole of electrons is 96,486 C (Faraday's constant).
  • 1 A = 1 C/s

The time  that it would take for 336 mg of copper to be plated at a current of 5.6 A is:

336mgCu \times \frac{1gCu}{1,000mgCu} \times \frac{1molCu}{63.55gCu} \times \frac{2mole^{-} }{1molCu} \times \frac{94,486C}{1mole^{-}} \times \frac{1s}{5.6C} = 1.8 \times 10^{2} s

3 0
3 years ago
List any two uses of Brass , Bronze , Sulphur , Iodine
NikAS [45]

BRASS :It is easy to form into various shapes, a good conductor of heat, and generally resistant to corrosion from salt water. 1 pipes and 2 tubes, 3 screws, 4 cartridge casings for firearms.

BRONZE :for bearings because of its friction properties, and as 1 musical instruments ,2 and medals

Sulphur :1 making car batteries, 2 fertilizer

IODINE :1 Iodine regulates skin moisture levels and aids in the healing of cuts and scars through cellular regeneration. 2 Iodine also regulates the hormones responsible for acne breakouts.3 Treating thyroid cancer.

5 0
3 years ago
If Lithium and Nitrogen created a bond what would the ratios be?
olga nikolaevna [1]

Answer:

There would be three Lithium atoms per one Nitrogen atom.

3:1

Li3N (Lithium Nitride)

Explanation:

Group 15 elements usually have 5 valence electrons, and every atom wants to have a full valence shell of valence electrons. So, nitrogen can get three electrons from each Lithium atom in order to get a full octet.

5 0
3 years ago
Read 2 more answers
The most abundant elements in the universe are hydrogen and helium, but there are also small but significant amounts of heavier
Stells [14]

Answer:

in nuclear fusion deep in the interiors of stars

Explanation:

Nuclear fusion -

It is the type of reaction , where two or more atomic nuclei of the atom merges together to release two or more different nuclei along with some subatomic particles , is referred to as a nuclear fusion reaction .

The reaction can very well be done on stars , because of very high energy .

Hence , a nuclear fusion occurs deep inside the stars .

7 0
3 years ago
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