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s2008m [1.1K]
2 years ago
10

What is the number of valence electrons in a calcium atom? * 8 2 18 20​

Chemistry
1 answer:
hoa [83]2 years ago
4 0

Answer:

2

Explanation:

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A 250 cm^3 solution containing 1,46 g of sodium chloride is added to an excess of silver nitrate solution. The reaction is given
faust18 [17]

Answer:

The mass of the precipitate  that AgCl is 3.5803 g.

Explanation:

a) To calculate the molarity of solution, we use the equation:

\text{Molarity of the solution}=\frac{\text{Mass of solute}\times 1000}{\text{Molar mass of solute}\times \text{Volume of solution (in mL)}}

We are given:

Mass of solute (NaCl) = 1.46 g

Molar mass of sulfuric acid = 58.5 g/mol

Volume of solution = 250 cm^3 =250 mL

1 cm^3= 1 ml

Putting values in above equation, we get:

\text{Molarity of solution}=\frac{1.46g\times 1000}{58.5g/mol\times 250}\\\\\text{Molarity of solution}=0.09982 M

0.09982 M is the concentration of the sodium chloride solution.

b) NaCl (aq)+AgNO_3 (aq)\rightarrow AgCI(s)+NaNO_3(aq)

Moles of NaCl = \frac{1.46 g}{58.5 g/mol}=0.02495 mol

according to reaction 1 mol of NaCl gives 1 mol of AgCl.

Then 0.02495 moles of NaCl will give:

\frac{1}{1}\times 0.02495 mol=0.02495 mol of AgCl

Mass of 0.02495 moles of AgCl:

0.02495 mol\times 143.5 g/mol=3.5803 g

The mass of the precipitate  that AgCl is 3.5803 g.

3 0
3 years ago
A scientist measures the standard enthalpy change for the following reaction to be -327.2 kJ : P4O10(s) 6 H2O(l)4H3PO4(aq) Based
OleMash [197]

Answer:

ΔH°f P4O10(s) = - 3115.795 KJ/mol

Explanation:

  • P4O10(s) + 6H2O(l) ↔ 4H3PO4(aq)
  • ΔH°rxn = ∑νiΔH°fi

∴ ΔH°rxn = - 327.2 KJ

∴ ΔH°f H2O(l) = - 285.84 KJ/mol

∴ ΔH°F H3PO4(aq) = - 1289.5088 KJ/mol

⇒ ΔH°rxn = (4)(- 1289.5088) - (6)(- 285.84) - ΔH°f P4O10(s) = - 327.2 KJ

⇒ ΔH°f P4O10(s) = - 5158.035 + 1715.04 + 327.2

⇒ ΔH°f P4O10(s) = - 3115.795 KJ/mol

5 0
3 years ago
Why does the sun appear to be the brightest star in the sky?
skelet666 [1.2K]

Answer:

D

Explanation:

There are only 2 ways to explain this.

distance

and brightness caused by what it is burning.

A is true but it is not the explanation of why it is true.

B this is actually not true. Other stars would burn much more.

C It is not the largest star. In fact it is in the lower middle.

D is the answer. 93 million miles as these things go, is not every much.

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3 years ago
What would the formula be for this model above?
Nadusha1986 [10]
Probably CH(subscript)4... :) It's Methane
4 0
3 years ago
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