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ehidna [41]
3 years ago
14

The unit "troy ounce" is often used for precious metals such as gold (Au) and platinum (Pt) (1 troy ounce= 31.103 g). (a) A gold

coin weighs 2.41 troy ounces. Calculate its mass in grams. (b) Is a troy ounce heavier or lighter than an ounce (1lb =16 oz; 1lb =453.6 g)?
Chemistry
1 answer:
frez [133]3 years ago
8 0

Answer:

Explanation:

a) 1 troy ounce is equal to 31.103 g

2.41 troy ounce is equal to 2.41 x 31.103 g

= 74.958 g

b) 1  ounce = 1 / 16 lb = 1/16 x 453.6 g = 28.35 g.

1 troy ounce = 31.103 g

so 1 troy ounce is heavier than 1 ounce.

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determine the mass number and the atomic number of a chlorine atom that has 17 protons and 18 neutrons.
Andrew [12]

Answer:

35.453 atomic mass units

You can use Phet (Atomic masses, Elements and more)  for Chemistry

8 0
3 years ago
Acetone can be easily converted to isopropyl alcohol by addition of hydrogen to the carbon–oxygen double bond. calculate the ent
Step2247 [10]

Answer:

-484kJ

Explanation:

Carry out bond energy calculation

[6(C-H) + (C=O) +2(C-C)] - [(O-H) +7(C-H)+ (C-O) +2(C-C)]

Substitute the bond energy values = -484kJ

7 0
3 years ago
Evaluate - if you put a scale in an elevator and weigh yourself as you ascend and the descend, does the scale have the same read
N76 [4]
No, when ascending, you would weigh more, and when you descend, you weigh less.

This is due to the difference in the effect of gravity.
4 0
3 years ago
Read 2 more answers
Combine the two half-reactions that give the spontaneous cell reaction with the smallest E∘. Fe2+(aq)+2e−→Fe(s) E∘=−0.45V I2(s)+
Iteru [2.4K]

<u>Answer:</u> The spontaneous cell reaction having smallest E^o is I_2+Cu\rightarrow Cu^{2+}+2I^-

<u>Explanation:</u>

We are given:

E^o_{(Fe^{2+}/Fe)}=-0.45V\\E^o_{(I_2/I^-)}=0.54V\\E^o_{(Cu^{2+}/Cu)}=0.34V

The substance having highest positive E^o potential will always get reduced and will undergo reduction reaction. Here, iodine will always undergo reduction reaction, then copper and then iron.

The equation used to calculate electrode potential of the cell is:

E^o_{cell}=E^o_{oxidation}+E^o_{reduction}

The combination of the cell reactions follows:

  • <u>Case 1:</u>

Here, iodine is getting reduced and iron is getting oxidized.

The cell equation follows:

I_2(s)+Fe(s)\rightarrow Fe^{2+}(aq.)+2I^-(aq.)

Oxidation half reaction:  Fe(s)\rightarrow Fe^{2+}(aq.)+2e^-   E^o_{oxidation}=0.45V

Reduction half reaction:  I_2(s)+2e^-\rightarrow 2I_-(aq.)   E^o_{reduction}=0.54V

E^o_{cell}=0.45+0.54=0.99V

Thus, this cell will not give the spontaneous cell reaction with smallest E^o_{cell}

  • <u>Case 2:</u>

Here, iodine is getting reduced and copper is getting oxidized.

The cell equation follows:

I_2(s)+Cu(s)\rightarrow Cu^{2+}(aq.)+2I^-(aq.)

Oxidation half reaction:  Cu(s)\rightarrow Cu^{2+}(aq.)+2e^-   E^o_{oxidation}=-0.34V

Reduction half reaction: I_2(s)+2e^-\rightarrow 2I_-(aq.)   E^o_{reduction}=0.54V

E^o_{cell}=-0.34+0.54=0.20V

Thus, this cell will give the spontaneous cell reaction with smallest E^o_{cell}

  • <u>Case 3:</u>

Here, copper is getting reduced and iron is getting oxidized.

The cell equation follows:

Cu^{2+}(aq.)+Fe(s)\rightarrow Fe^{2+}(aq.)+Cu(s)

Oxidation half reaction:  Fe(s)\rightarrow Fe^{2+}(aq.)+2e^-   E^o_{oxidation}=0.45V

Reduction half reaction:  Cu^{2+}(aq.)+2e^-\rightarrow Cu(s)   E^o_{reduction}=0.34V

E^o_{cell}=0.45+0.34=0.79V

Thus, this cell will not give the spontaneous cell reaction with smallest E^o_{cell}

Hence, the spontaneous cell reaction having smallest E^o is I_2+Cu\rightarrow Cu^{2+}+2I^-

7 0
3 years ago
What are the concentrations of hydroxide and hydronium ions in a solution with a pH of 8.3?
Elza [17]

Answer:

[H⁺] = 5.012 x 10⁻⁹. & [OH⁻] = 1.995 x 10⁻⁶.

Explanation:

∵ pH = - log[H⁺]

8.3 = - log[H⁺]

∴ log[H⁺] = - 8.3.

<em>∴ [H⁺] = 5.012 x 10⁻⁹.</em>

∵ [H⁺][OH⁻] = 10⁻¹⁴.

<em>∴ [OH⁻] = 10⁻¹⁴/[H⁺] </em>= 10⁻¹⁴/(5.012 x 10⁻⁹) = <em>1.995 x 10⁻⁶.</em>

7 0
4 years ago
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