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3 years ago

9

Which of the following best describes the process of electroplating?

1 answer:

sweet-ann [11.9K]3 years ago

7 0

I think the correct answer would be B. The process of electroplating uses a direct current in order to give a cheap metal the apperance and resistance of a more expensive metal by coating it with a certain metal. The current reduces the dissolved metal ions to form a thin coating on a surface.

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Which of the following is the best instrument to use to prepare a solution?

Taya2010 [7]

What are the options?

4 0

3 years ago

In which reaction does the oxidation number of hydrogen change? In which reaction does the oxidation number of hydrogen change?

dedylja [7]

<u>Answer:</u> The correct answer is $2Na(s)+2H_2O(l)\rightarrow 2NaOH(aq.)+H_2(g)$

<u>Explanation:</u>

Oxidation number is defined as the number which is given to an atom when it looses or gains electron. When an atom looses electron, it attains a positive oxidation state. When an atom gains electron, it attains a negative oxidation state.

Oxidation state of the atoms in their elemental state is considered as 0. Hydrogen is present as gaseous state.

For the given chemical reactions:

<u>Reaction 1:</u> $2HClO_4(aq.)+CaCO_3(s)\rightarrow Ca(ClO_4)_2(aq.)+H_2O(l)+CO_2 (g)$

Oxidation state of hydrogen on reactant side: +1

Oxidation state of hydrogen on product side: +1

Thus, the oxidation state of hydrogen is not changing.

<u>Reaction 2:</u> $CaO(s)+H_2O(l)\rightarrow Ca(OH)_2(s)$

Oxidation state of hydrogen on reactant side: +1

Oxidation state of hydrogen on product side: +1

Thus, the oxidation state of hydrogen is not changing.

<u>Reaction 3:</u> $HCl(aq.)+NaOH(aq.)\rightarrow NaCl(aq.)+H_2O(l)$

Oxidation state of hydrogen on reactant side: +1

Oxidation state of hydrogen on product side: +1

Thus, the oxidation state of hydrogen is not changing.

<u>Reaction 4:</u> $2Na(s)+2H_2O(l)\rightarrow 2NaOH(aq.)+H_2(g)$

Oxidation state of hydrogen on reactant side: +1

Oxidation state of hydrogen on product side: 0

Thus, the oxidation state of hydrogen is changing.

<u>Reaction 5:</u> $SO_2(g)+H_2O(l)\rightarrow H_2SO_3(aq.)$

Oxidation state of hydrogen on reactant side: +1

Oxidation state of hydrogen on product side: +1

Thus, the oxidation state of hydrogen is not changing.

Hence, the correct answer is $2Na(s)+2H_2O(l)\rightarrow 2NaOH(aq.)+H_2(g)$

6 0

3 years ago

Calculate the pOH of a solution that contains 3.9 x 10-5 M H3O+ at 25°C.

exis [7]

Answer:

Option b. 9.59

Explanation:

First, let us calculate the pH. This is illustrated below:

[H3O+] = 3.9 x 10-5 M

pH = —Log [H3O+]

pH = —Log [3.9 x 10-5]

pH = 4.41

Recall: pH + pOH = 14

4.41 + pOH = 14

Collect like terms

pOH = 14 — 4.41

pOH = 9.59

6 0

4 years ago

Seriously don't understand this worksheet at all please help!

sergij07 [2.7K]

I’m in the 5th grade yo

8 0

3 years ago

calculate the change in enthalpy, if the reactants have an enthalpy of 315 kj and the products have an enthalpy of 375 kj

sineoko [7]

25% is the answer, i believe.

5 0

3 years ago