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3 years ago

Please i need help understanding the facts about ions. and whats the answer??

Chemistry

1 answer:

Degger [83]3 years ago

6 0

All are true except the statement that ions are formed by changing the number protons in an atom’s nucleus.

A neutral atom contains the same number of protons (positive charge) and electrons (negative charge).

If there are more electrons than protons, the atom becomes a negative ion.

If there are fewer electrons than protons, the atom becomes a positive ion.

The protons are in the nucleus, where we can’t easily get at them. The electrons are outside the nucleus, so other chemicals can easily get at them and either remove them or add to their number.

Metals have only a few valence electrons, so it is fairly easy to remove them and form positive ions.

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A solution contains 0.0440 M Ca2 and 0.0940 M Ag. If solid Na3PO4 is added to this mixture, which of the phosphate species would

Olenka [21]

Answer:

C. $Ca_3(PO_4)_2$ will precipitate out first

the percentage of $Ca^{2+}$ remaining = 12.86%

Explanation:

Given that:

A solution contains:

$[Ca^{2+}] = 0.0440 \ M$

$[Ag^+] = 0.0940 \ M$

From the list of options , Let find the dissociation of $Ag_3PO_4$

$Ag_3PO_4 \to Ag^{3+} + PO_4^{3-}$

where;

Solubility product constant Ksp of $Ag_3PO_4$ is $8.89 \times 10^{-17}$

Thus;

$Ksp = [Ag^+]^3[PO_4^{3-}]$

replacing the known values in order to determine the unknown ; we have :

$8.89 \times 10 ^{-17} = (0.0940)^3[PO_4^{3-}]$

$\dfrac{8.89 \times 10 ^{-17}}{(0.0940)^3} = [PO_4^{3-}]$

$[PO_4^{3-}] =\dfrac{8.89 \times 10 ^{-17}}{(0.0940)^3}$

$[PO_4^{3-}] =1.07 \times 10^{-13}$

The dissociation of $Ca_3(PO_4)_2$

The solubility product constant of $Ca_3(PO_4)_2$ is $2.07 \times 10^{-32}$

The dissociation of $Ca_3(PO_4)_2$ is :

$Ca_3(PO_4)_2 \to 3Ca^{2+} + 2 PO_{4}^{3-}$

Thus;

$Ksp = [Ca^{2+}]^3 [PO_4^{3-}]^2$

$2.07 \times 10^{-33} = (0.0440)^3 [PO_4^{3-}]^2$

$\dfrac{2.07 \times 10^{-33} }{(0.0440)^3}= [PO_4^{3-}]^2$

$[PO_4^{3-}]^2 = \dfrac{2.07 \times 10^{-33} }{(0.0440)^3}$

$[PO_4^{3-}]^2 = 2.43 \times 10^{-29}$

$[PO_4^{3-}] = \sqrt{2.43 \times 10^{-29}$

$[PO_4^{3-}] =4.93 \times 10^{-15}$

Thus; the phosphate anion needed for precipitation is smaller i.e $4.93 \times 10^{-15}$ in $Ca_3(PO_4)_2$ than in $Ag_3PO_4$ $1.07 \times 10^{-13}$

Therefore:

$Ca_3(PO_4)_2$ will precipitate out first

To determine the concentration of $[Ca^+]$ when the second cation starts to precipitate ; we have :

$Ksp = [Ca^{2+}]^3 [PO_4^{3-}]^2$

$2.07 \times 10^{-33} = [Ca^{2+}]^3 (1.07 \times 10^{-13})^2$

$[Ca^{2+}]^3 = \dfrac{2.07 \times 10^{-33} }{(1.07 \times 10^{-13})^2}$

$[Ca^{2+}]^3 =1.808 \times 10^{-7}$

$[Ca^{2+}] =\sqrt[3]{1.808 \times 10^{-7}}$

$[Ca^{2+}] =0.00566$

This implies that when the second cation starts to precipitate ; the concentration of $[Ca^{2+}]$ in the solution is 0.00566

Therefore;

the percentage of $Ca^{2+}$ remaining = concentration remaining/initial concentration × 100%

the percentage of $Ca^{2+}$ remaining = 0.00566/0.0440 × 100%

the percentage of $Ca^{2+}$ remaining = 0.1286 × 100%

the percentage of $Ca^{2+}$ remaining = 12.86%

5 0

3 years ago

3. Matter with a composition that is always the same is a(n) substance mixture compound

Andre45 [30]

Answer:

substance

Explanation:

A pure substance is a form of matter that has a constant composition (meaning it's the same everywhere) and properties that are constant throughout the sample (meaning there is only one set of properties such as melting point, color, boiling point, etc

7 0

3 years ago

One method for preparing pure iron from Fe2O3 is by reaction with carbon monoxide.Fe2O3(s)+CO(g)→Fe(s)+CO2(g) How many moles of

larisa [96]

Answer:

The 2292 moles of CO are needed to react completely with 122 Kg of Fe₂O₃.

Explanation:

Given data:

Mass of Fe₂O₃ = 122 Kg ( 122×1000 = 122000 g)

Moles of CO = ?

Solution:

Chemical equation:

Fe₂O₃ + 3CO → 2Fe + 3CO₂

Number of moles of Fe₂O₃:

Number of moles = mass/ molar mass

Number of moles = 122000 g /159.69 g/mol

Number of moles = 764 mol

Now we will compare the moles of Fe₂O₃ with CO.

Fe₂O₃ : CO

1 : 3

764 : 3×764 =2292 mol

The 2292 moles of CO are needed to react completely with 122 Kg of Fe₂O₃.

6 0

3 years ago

All of the following are true regarding alcoholic fermentation, except that alcoholic fermentation

guapka [62]

A. produces as much energy as cell respiration.

4 0

3 years ago

During which step in "Steps to Solve a Problem” should students pick a strategy to use? Step 1 Step 2 Step 3 Step 4

Feliz [49]

Answer:

Step 3

Explanation:

I am back sorry it took me so long, I believe its Step 3 because that's were you chose your strategy, you use it in Step 4, but if its not Step 3 its Step 4

1. identifying

problem solving step: 1)__ the problem is most difficult: not in habit of asking what the problem really is; in the habit of reacting or giving up

2. representing

problem solving step: 2) __ the problem: abstract or external representation

3. strategy

problem solving step: 3) selecting an appropriate __; trial and error vs means-ends analysis

4. implementing

problem solving step: 4) __ the strategy; dependent on previous steps

8 0

3 years ago

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