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3 years ago

40 Points!!! Match the correct definition with the correct keyword.

Chemistry

1 answer:

My name is Ann [436]3 years ago

8 0

Answer:

Okay the Answers are top to bottom.

5, 4, 1, 3, 2

Explanation:

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When doing a recrystallization what observations would prompt you to perform a hot filtration?

KATRIN_1 [288]

Answer is: <span>because dissolved compounds can crystallizing from solution during filtration and forming crystals on the filter paper or funnel.
</span>Recrystallization<span> is a technique used to purify chemicals by dissolving both impurities and a compound in an appropriate solvent, either compound or impurities can be removed from the solution, leaving the other behind.</span>

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4 years ago

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Explain how interactions can be both beneficial and harmful to the organism in a community

Marysya12 [62]

Interactions to an organism can be both harmful and beneficial due to the organism's circumstances. For example by adding tadpoles to an eco system it results in the tadpoles eating all the food thus killing the other organisms. Whereas by adding plants to an ecosystem it provides shelter for the organisms and possibly food being beneficial.

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4 years ago

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As a technician in a large pharmaceutical research firm, you need to produce 250. mL of a potassium dihydrogen phosphate buffer

Reika [66]

Answer:

We will need 147.772 mL of KH2PO4 to make this solution

Explanation:

For this case we can give the following equation:

H2PO4 - ⇄ H+ + HPO42-

With following pH- equation:

pH = pKa + log [HPO42-]/[H2PO4-]

7.05 = 7.21 + log [HPO42-]/[H2PO4-]

-0.16 = log [HPO42-]/[H2PO4-]

10^-0.16 = [HPO42-]/[H2PO4-]

0.6918 = [HPO42-]/[H2PO4-]

Let's say the volume of HPO42-= x then the volume of H2PO4- will be 250 mL - x

Since both have a concentration of 1M = 1 mol /L

If we plug this in the equation 0.6918 = [HPO42-]/[H2PO4-]

0.6918 = x / (250 - x)

0.6918*250 - 0.6918x = x

172.95 = 1.6918x

x = 102.228 mL

The volume of HPO42- = 102.228 mL

Then the volume of H2PO4- = 250 - 102.228 = 147.772 mL

To control this we can plug this in the pH equation

7.05 = 7.21 + log [HPO42-]/[H2PO4-]

7.05= 7.21 + log (102.228 / 147.772) = 7.05

We will need 147.772 mL of KH2PO4 to make this solution

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3 years ago

Which of earth's spheres is most affected by weathering and erosion

Natali [406]

Answer: the hydrosphere

Explanation:

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3 years ago

When a glow stick is crushed and shaken, the two liquids mix and the stick glows.

Mars2501 [29]

Answer:

A chemical change has occurred, with energy being given off.

Explanation:

The liquids mix and the stick gives off energy in light form

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3 years ago