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4 years ago

By 1700, how many elements had scientists discovered and isolated?

Chemistry

1 answer:

mariarad [96]4 years ago

8 0

Answer:

By 1700, 13 elements had been discovered and isolated by the Scientists.

Option (a)

Explanation:

The copper, gold and silver are the elements which have been known from thousands of years. In the early days of 1700, the scientist discovered only 12 elements, later on one more element was discovered.

Later in the era of 1800, the scientist research and find new elements, where they organize it methodically, according to the physical and chemical properties.

After a long research in 1900 scientist discovered more than 80 elements.

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For the generic equilibrium HA(aq) ⇌ H+(aq) + A−(aq), which of these statements is true? For the generic equilibrium , which of

timama [110]

Answer: The correct statement is if you add the soluble salt KA to a solution of HA that is at equilibrium, the pH would increase.

Explanation:

Common ion effect is defined as the effect which occurs on equilibrium when a common ion (an ion which is already present in the solution) is added to a solution. This effect generally decreases the solubility of a solute.

Equilibrium reaction of HA and KA follows the equation:

$HA\rightleftharpoons H^{+}(aq.)+A^{-}(aq.)$

$KA\rightleftharpoons K^+(aq.)+A^{-}(aq.)$

According to Le-Chateliers principle, if there is any change in the variables of the reaction, the equilibrium will shift in the direction in order to minimize the effect.

In the equilibrium reactions, $A^-$ ion is getting increased on the product side, so the equilibrium will shift in the direction to minimize this effect, which is in the direction of HA.

Thus, the addition of KA will shift the equilibrium in the left direction.

Equilibrium constant depends on the temperature of the system. It does not have any effect on any change of pH.

pH is defined as the negative logarithm of hydrogen ions present in the solution

If the solution has high hydrogen ion concentration, then the pH will be low.
If the solution has low hydrogen ion concentration, then the pH will be high.

As, the equilibrium is shifting in the left direction, that means concentration of $H^+$ ions are getting decreases. This will increase the pH of the solution.

Hence, the correct statement is if you add the soluble salt KA to a solution of HA that is at equilibrium, the pH would increase.

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4 years ago

The formation of iodine is described by the following chemical equation:

olga nikolaevna [1]

Answer:

N2O2(g) +O2(g) ===> 2NO2(g)

Explanation:

For a nonelementary reaction, the reaction equation is described as the sum of all the steps involved. All these steps constitute the reaction mechanism. Each step in the mechanism is an elementary reaction. The rate law of the overall reaction involves the rate determining step (slowest step) in the reaction sequence.

Now look at the overall reaction 2NO(g) + O2(g) ---------> 2NO2(g)

The two steps in the mechanism are

2NO(g) --------->N2O2(g) (fast)

N2O2(g) +O2(g) -------> 2NO2(g) (slow)

Summing all the steps and cancelling out the intermediate N2O2(g), we obtain the reaction equation;

2NO(g) + O2(g) ---------> 2NO2(g)

Hence the answer.

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3 years ago

If a jar of honey sits for a long time, sugar may crystallize in the jar. Describe two possible causes for the crystallization.

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Dryness and temperature are the primary reasons but also the type of honey.

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4 years ago

1362205.2 in scientific notation

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3 years ago

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Answer:

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Explanation:

This question is asking to write and balance an equation between between aqueous sodium carbonate (Na2CO3) and aqueous nitric acid (HNO3). The equation is as follows:

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