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Mazyrski [523]
3 years ago
10

Three test tubes contain white crystalline organic solids A, B, and C, each of which melts at 149-150 degrees C. A 50-50 mixture

of A and B melts at 130-139 degrees C. A 50-50 mixture of A and C melts at 149-150 degrees C. In what range would a 50-50 mixture of B and C probably melt? What can you say about the identities of A, B, and C?
Chemistry
1 answer:
Digiron [165]3 years ago
3 0

Answer:

The mixture of B and C will melt as 130 - 139 ºC.

Explanation:

If the melting point (130 - 139 ºC) of a mixture of A and B is lower than the pure substances that is 149 - 150 ºC that means that one of these susbtances is an impurity because reduces the melting point.

If the melting point of the mixture of A and C is the same as the pure substances, we can deduce that they are the same substances, also because the melting point when a substance is pure is just 1 or 2 ºC like in this case.

So in a Mixture of B and C is going to be like the first case of the mixture among A and B, because the B substance is the impurity.

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Balance the following skeleton reaction and identify the oxidizing and reducing agents: Include the states of all reactants and
N76 [4]

Answer:

Oxidizing agent - CrO4^2-

Reducing agent- N2O

Explanation:

Let us look at the equation closely;

CrO4^2- (aq) + 3N2O(g) ------------> Cr^3+ (aq) + 3NO(g) [acidic]

The reduction half equation is;

CrO4^2- (aq) + 3e -------->Cr^3+ (aq)

Oxidation half equation is;

3N2O(g) ------>3 NO(g) +3 e

Note that the oxidizing agent participates in the reduction half equation while the reducing agent participates in the oxidation half equation as seen above.

8 0
3 years ago
A solution of Na2CO3 is added dropwise to a solution that contains 1.15×10−2 M Fe2+ and 0.58×10−2 M Cd2+. What concentration of
castortr0y [4]

The question is incomplete, complete question is;

A solution of Na_2CO_3 is added dropwise to a solution that contains1.15\times 10^{-2} M of Fe^{2+} and 0.58\times 10^{-2} M and Cd^{2+}.

What concentration of CO_3^{2-} is need to initiate precipitation? Neglect any volume changes during the addition.

K_{sp} value FeCO_3: 2.10\times 10^{-11}

K_{sp} value CdCO_3: 1.80\times 10^{-14}

What concentration of CO_3^{2-} is need to initiate precipitation of the first ion.

Answer:

Cadmium carbonate will precipitate out first.

Concentration of CO_3^{2-} is need to initiate precipitation of the cadmium (II) ion is 3.103\times 10^{-12} M.

Explanation:

1) FeCO_3\rightleftharpoons Fe^{2+}+CO_3^{2-}

The expression of an solubility product of iron(II) carbonate :

K_{sp}=[Fe^{2+}][CO_3^{2-}]

2.10\times 10^{-11}=0.58\times 10^{-2} M\times [CO_3^{2-}]

[CO_3^{2-}]=\frac{2.10\times 10^{-11}}{1.15\times 10^{-2} M}

[CO_3^{2-}]=1.826\times 10^{-9}M

2) CdCO_3\rightleftharpoons Cd^{2+}+CO_3^{2-}

The expression of an solubility product of cadmium(II) carbonate :

K_{sp}=[Cd^{2+}][CO_3^{2-}]

1.80\times 10^{-14}=0.58\times 10^{-2} M\times [CO_3^{2-}]

[CO_3^{2-}]=\frac{1.80\times 10^{-14}}{0.58\times 10^{-2} M}

[CO_3^{2-}]=3.103\times 10^{-12} M

On comparing the concentrations of carbonate ions for both metallic ions, we can see that concentration to precipitate out the cadmium (II) carbonate from the solution is less than concentration to precipitate out the iron (II) carbonate from the solution.

So, cadmium carbonate will precipitate out first.

And the concentration of carbonate ions to start the precipitation of cadmium carbonate we will need concentration of carbonate ions greater than the 3.103\times 10^{-12} M concentration.

6 0
3 years ago
HELP ME PLEASE WILL MAKE AS BRAINLIES
vredina [299]
1. a 2.b 3 a 4. c. 4.a 5. d 6.a. 2Na + Cl2 2NaC 7.c. 3 8.3 9.b
7 0
3 years ago
_______ is the amount of heat necessary to raise the temperature of 1 gram of a substance by 1 degree Kelvin. A. A calorie B. En
Maksim231197 [3]
<h2>The required option d) "specific heat" is correct.</h2>

Explanation:

  • To raise the temperature of any substance or material of certain mass to respective temperature it requires some amount of heat.
  • Specific heat is the amount of heat necessary to raise the temperature of the substance of 1 gram to 1 Kelvin.
  • It is the amount of heat which is required to raise the temperature per unit mass to per unit temperature.
  • Thus, the required "option d) specific heat" is correct.
5 0
3 years ago
Use the Gizmo to estimate the age of each of the objects below. For these questions, each second in the Gizmo represents 1,000 y
ziro4ka [17]

Answer:

Check the explanation

Explanation:

AT = A0 e(-T/H)

... where A0 is the starting activity, AT is the activity at some time T, and H is the half-life, in units of T.

Substituting what we know, we get...

0.71 = (1) e(-T/5730)

Solve for T...

loge(0.71) = -T/5730

T = -loge(0.71)(5730)

T = 1962 (conservatively rounded, T = 2000)

similarly for all

for aboriginal charcoal

0.28 = (1) e(-T/5730)

Solve for T...

loge(0.28) = -T/5730

T = -loge(0.28)(5730)

T = 7294 (conservatively rounded, T = 7000)

for mayan headdress

0.89 = (1) e(-T/5730)

Solve for T...

loge(0.89) = -T/5730

T = -loge(0.89)(5730)

T = 667 (conservatively rounded, T = 700)

for neanderthal

0.05 = (1) e(-T/5730)

Solve for T...

loge(0.05) = -T/5730

T = -loge(0.05)(5730)

T = 17165 (conservatively rounded, T = 17000)

7 0
3 years ago
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