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3 years ago

Hydrogen and oxygen react to form water. At an atomic level, how do we know that a chemical reaction has occurred

1 answer:

3 0

Answer: Bubbles are evidence that a chemical reaction took place because cause formation of a precipitate. Bubbles are evidence that a chemical reaction took place because they indicate the formation of gas as a new product.

Explanation:

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What is the Ka of a weak acid (HA) if the initial concentration of weak acid is 4.5 x 10-4 M and the pH is 6.87? (pick one)

rewona [7]

Answer:

Ka = $4.04 \times 10^{-11}$

Explanation:

Initial concentration of weak acid = $4.5 \times 10^{-4}\ M$

pH = 6.87

$pH = -log[H^+]$

$[H^+]=10^{-pH}$

$[H^+]=10^{-6.87}=1.35 \times 10^{-7}\ M$

HA dissociated as:

$HA \leftrightharpoons H^+ + A^{-}$

(0.00045 - x) x x

[HA] at equilibrium = (0.00045 - x) M

x = $1.35 \times 10^{-7}\ M$

$Ka = \frac{[H^+][A^{-}]}{[HA]}$

$Ka = \frac{(1.35 \times 10^{-7})^2}{0.00045 - 0.000000135}$

0.000000135 <<< 0.00045

$Therefore, Ka = \frac{(1.35 \times 10^{-7})^2}{0.00045 } = 4.04 \times 10^{-11}$

5 0

3 years ago

If the value for ΔS is postive, and the value for ΔH is negative, thr reaction will be

dmitriy555 [2]

It follows that the reaction is spontaneous at high temperatures Option A.

The term ΔS is referred to as the change in the entropy of the system. Now recall that entropy is defined as the degree of disorderliness in a system. If a system is highly disorderly then it means that it has a high entropy. Also, ΔH has to do with the heat change that accompanies a reaction.

We know that both the entropy and the heat change can both either be positive or negative. Now we know that the equation ΔG = ΔH - TΔS can be used to ascertain whether or not a reaction will be spontaneous. If the result is negative, then the reaction will be spontaneous.

As such, when then it follows that the reaction is spontaneous at high temperatures Option A.

Learn more about spontaneous reaction:brainly.com/question/13790391

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6 0

1 year ago

What state of matter is Polaris, the north star?

Anni [7]

The state of matter of Polaris, the north star is gas.

<h3>What are stars made of?</h3>

Stars are made up of a mixture of hot gases.

The mixture consists of helium and hydrogen. Hydrogen burns into helium to give starts a shining appearance when observed from a far distance.

Thus, the state of matter of all stars, including the north star, is gas.

More on stars can be found here: brainly.com/question/21521087

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8 0

2 years ago

Lithium carbonate, li2co3, contains 18.8 % lithium and is used in the treatment of mental illnesses such as bipolar disorder. wh

masha68 [24]

Assuming that the percentage composition is on the basis of weight percentage, therefore the mass of lithium would simply be the product of the two, that is:
mass Lithium = 0.188 * 1.70 g
mass Lithium = 0.3196 g = 0.32 g

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3 years ago

What is chemistry n laboratory

grin007 [14]

a laboratory for research in chemistry. chem lab, chemistry lab. lab, laboratory, research lab, research laboratory, science lab, science laboratory - a workplace for the conduct of scientific research.

3 0

3 years ago