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Nookie1986 [14]
3 years ago
8

Which of the following is an indication of a chemical reaction?

Chemistry
1 answer:
vovikov84 [41]3 years ago
7 0

Answer:

All of the above

Explanation:

Their all chemical change

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A weak monoprotic acid is titrated with 0.100 MNaOH. It requires 50.0 mL of the NaOH solution to reach the equivalence point. Af
larisa86 [58]

Explanation:

The given reaction is as follows.

        HA(aq) + NaOH (aq) \rightleftharpoons NaA(aq) + H_{2}O(l)

Hence, number of moles of NaOH are as follows.

        n = 0.05 L \times 0.1 M

           = 0.005 mol

After the addition of 25 ml of base, the pH of a solution is 3.62. Hence, moles of NaOH is 25 ml base are as follows.

             n = 0.025 L \times 0.1 M

                = 0.0025 mol

According to ICE table,

         HA(aq) + NaOH (aq) \rightleftharpoons NaA(aq) + H_{2}O(l)

Initial:     0.005 mol   0.0025 mol              0                  0

Change: -0.0025 mol  -0.0025 mol        +0.0025 mol

Equibm:   0.0025 mol    0                         0.0025 mol

Hence, concentrations of HA and NaA are calculated as follows.

          [HA] = \frac{0.0025 mol}{V}

        [NaA] = \frac{0.0025 mol}{V}

       [A^{-}] = [NaA] = \frac{0.0025 mol}{V}

Now, we will calculate the pK_{a} value as follows.

          pH = pK_{a} + log \frac{A^{-}}{HA}

       pK_{a} = pH - log \frac{[A^{-}]}{[HA]}

                  = 3.42 - log \frac{\frac{0.0025 mol}{V}}{\frac{0.0025}{V}}

                  = 3.42

Thus, we can conclude that pK_{a} of the weak acid is 3.42.

           

8 0
3 years ago
At Jim's auto shop, it takes him minutes to do an oil change and minutes to do a tire change. Let be the number of oil changes h
Juli2301 [7.4K]

Answer:

The total time that Jim needs to change x oil changes and y tire changes is less than 180 min.

The time needed for x oil changes is 12 * x.

The time needed for y tire changes is 18 * y.

The total time is the sum of the above times and needs to be less than 180 that is

12 * x + 18 * y < 180 divide both sides of equation by 6

12/6 * x + 18/6*y < 180/6

2*x + 3*y < 30

2*x < 30 - 3*y divide both sides by 2 to get the inequality for x

x < 30/2 - 3/2*y = 15 - 1.5 y < 15 that is x < = 15

2*x + 3*y < 30

3*y < 30 - 2*x divide both sides by 3 to get the inequality for y

y < 30/3 - 2/3 *x = 10 - 2/3*x < 10 that is y < = 10

Also we can write x + y < x+ 3/2 * y < 15.

Explanation:

Jim's can do not more then 5 oil changes and not more then 10 tire changes or all together she can do not more then 15 total of oil and tire changes.

5 0
3 years ago
In the 1800s, a popular belief known as vitalism stated that life processes could not be explained by the laws of physics and ch
soldi70 [24.7K]

The question is incomplete, the complete question is;

In the 1800s, a popular belief known as vitalism stated that life processes could not be explained by the laws of physics and chemistry,and were instead dictated by an independent life force. Which discovery most likely caused scientists to revise this hypothesis regarding the origin of life on Earth?

a. that inorganic compounds existed within live organisms

b. that organic compounds could be synthesized in a laboratory

c. that RNA could serve as a template to synthesize DNA

d. that self-replicating molecules existed inside cells

Answer:

b. that organic compounds could be synthesized in a laboratory

Explanation:

Vitalism is the belief that "living organisms are fundamentally different from non-living entities because they contain some non-physical element or are governed by different principles than are inanimate things"(wikipedia).

This theory held that the molecules involved in life processes could not be synthesized in the laboratory.

All these were upturned after Fredrich Whöler's synthesis of urea in 1828. He was able to show that molecules involved in life process can also be synthesized in the laboratory. This gave rise to modern synthetic organic chemistry.

6 0
3 years ago
What do El Niño and La Niña have in common? Check all that apply.
Yakvenalex [24]
Can you post a picture of that the checkings are
7 0
3 years ago
Read 2 more answers
A system gains 652 kJ of heat, resulting in a change in internal energy of the system equal to +241 kJ. How much work is done?
levacccp [35]

Answer:

-411 kj

Explanation:

We solve by using this formula

∆U = ∆Q + ∆W

This formula is the first law of thermodynamics

Change in internal energy U = +241

Heat gained by system Q = 652

Putting the value into the equation

+241 = 652 + W

Workdone = 241 - 652

Workdone = -411 kj

Since work done is negative it means that work was done by the system

3 0
3 years ago
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