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3 years ago

How many calcium atoms would be in a 100 g sample of calcium

Chemistry

1 answer:

KengaRu [80]3 years ago

4 0

The number of calcium atoms that would be in a 100 g sample of calcium is 1.505 x 10²⁴ atoms

calculation

Step 1 ; find the moles of calcium

moles = mass÷ molar mass

from periodic table the molar mass of Ca =40 g/mol

moles is therefore = 100 g÷ 40 g/mol = 2.5 moles

Step 2: use the Avogadro's law constant to determine the number of atoms of Calcium

That is According Avogadro's law 1 mole = 6.02 × 10²³ atoms

2.5 moles=? atoms

{(2.5 moles × 6.02×10²³ atoms) / 1 mole} = 1.505 × 10²⁴ atoms

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What is the h oh ph and poh of a 0.005m solution of calcium hydroxide?

fiasKO [112]

Answer: $[OH^{-}]= 0.01M or 1.0\times 10^{-2}M$

$[H^{+}]= 1.0\times 10^{-12}M$

pH = 12

pOH = 2

Explanation: Calcium hydroxide ( $Ca(OH)_{2}$ ) is a strong base that dissociates completely.

Dissociation equation of Calcium hydroxide is :

$Ca(OH)_{2} \rightarrow Ca^{+2} + 2OH^{-}$

1. Concentration of [OH-]

1 mol $Ca(OH)_{2}$ produces 2 mol OH- ions.

The given solution is 0.005M $Ca(OH)_{2}$ , then concentration of OH- would be twice the concentration of $Ca(OH)_{2}$

$[OH^{-}] = 0.005\times 2$ = 0.01M or $1.0\times 10^{-2}M$

2.Concentration of [H+]

Concentration of [H+] can be calculated by the formula: $[H^{+}] = \frac{Kw}{[OH^{-}]}$

kw = ionic product of water and its values is $(1\times 10^{-14})$

[OH-] = 0.01 M or $1.0\times 10^{-2}M$

$[H^{+}] = \frac{(1\times 10^{-14})}{[OH^{-}]}$

$[H^{+}] = \frac{(1\times 10^{-14})}{[0.01]}$

$[H^{+}] = 1.0\times 10^{-12}M$

3. pH value

pH is calculated by the formula : $pH = -log[H^{+}]$

$pH = -log[1.0\times 10^{-12}]$

pH = 12

4. pOH value

pOH is calculated by the formula : pOH = 14 - pH

pOH = 14 - 12

pOH = 2

pOH can also be calculated by using a different formula which is :

$pOH = -log(OH^{-})$

$pOH = -log(0.01)$

pOH = 2.

3 0

3 years ago

You react 2.33 g of iron (III) chloride with 50.0 mL of 0.500 M solution of sodium phosphate to

nikklg [1K]

Answer:

2.33g of iron (iii) chloride

50.0 mL of 5.00 M of sodium phosphate

FeCl3 + Na3PO4 > Fe(PO4) + 3NaCl

mol = conc × vol = 0.5 × 50/1000 = 0.025 mol Na3PO4

from the equation:

1 mol of Na3PO4 reacts with 1 mol FeCl3 = 3 mol of NaCl

0.025 mol = x

x = 0.0025 × 3 = 0.075 mol NaCl

mass = 0.075 g × 59 g/mol = 4.425 g NaCl

i guessed all of this so i dont know i it is correct

3 0

3 years ago

If a solid forms when two ionic solutions are mixed together in a test tube, what does this indicate?

Ira Lisetskai [31]

If a solid forms when two ionic solutions are mixed together in a test tube, it is an indication of a chemical change

The precipitaion os the solid indicates that a new product has been formed which is not soluble.

When a solid ionic compound is put in water, the compound is dissolved by ionizing (the ions separate and remain in aqueous phase). If you combine two ionic solutions and see a solid precipiate is becasue the ions have combined and form a new compound which is not soluble.

8 0

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Which materials are made of more than one element

Vinil7 [7]

Compound usually are

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3 years ago

A high jump is 6 feet, 10 1/4 inches. What is the high jump in meters? Its 2.09 but i need someone to show me how i would explai

andreyandreev [35.5K]

A high jump is 6 feet and 10 1/4 inches.

1 meter = 3.28084 feet
1 meter = 39.3701 inches

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3.28084 ft 3.28084

10 1/4 inches ⇒ ((10*4)+1)/4 = 41/4 inches

41 inches x 1 meter = 41 meter = 41 meter = 0.2603 meters
4 39.3701 inches 4 * 39.3701 157.4804

1.82879 meters * this was the equivalent of 6 feet
 + 0.26030 meters * equivalent of 10 1/4 inches
2.08909 meters

rounded to 2.09 meters.

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4 years ago