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Lana71 [14]
2 years ago
11

Ben and Jerry were testing powders in science lab. First they put the powder in a zip lock bag. Next they added some water. The

powder fizzed and bubbled; soon it disappeared. When the bubbling stopped the bag contained a clear liquid and a lot of gas. What is the MOST OBVIOUS sign of a chemical change in this reaction. A) A gas was produced. B) The powder mixed with the water. C) There was a change in temperature. D) The powder dissolved in the water.
Chemistry
2 answers:
tangare [24]2 years ago
8 0
A) because when gas is produced it changes chemical form whereas the chemical change is obvious.
Montano1993 [528]2 years ago
5 0

Answer:

A) A gas was produced.

Explanation:

In a chemical change there is always a change in the chemical composition. When reactant reacts with one another new products are formed, the products have a different chemical composition than the reactants.  Option A is correct as gases have evolved as a result of chemical change.

Option B and D are physical changes therefore incorrect. When matter dissolves in water or mixes with another substance there is no change in the chemical composition of the said matter.

Option C is incorrect as change in temperature is a change in the kinetic energy of matter and is not a chemical change.

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Can somebody help and answer which ones are connected to each other. Correctly!
igor_vitrenko [27]

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fossil fuels--burned to provide energy that is....

renewable energy--energy that with come back after use

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steam--nuclear reactors....

I'm not sure but I tried lol,lemme know if I'm wrong :D

3 0
3 years ago
What concentration of monosodium phosphate would be required to make a solution of pH 7.4 with 0.2 M disodium phosphate ( pKa
denis-greek [22]

Answer:

The concentration of monosodium phosphate is 0.1262M

Explanation:

The buffer of H₂PO₄⁻ / HPO₄²⁻ (Monobasic phosphate and dibasic phosphate has a pKa of 7.2

To determine the pH you must use Henderson-Hasselbalch equation:

pH = pKa + log [A⁻] / [HA]

<em>Where [A⁻] is molarity of the conjugate base of the weak acid, [HA].</em>

For H₂PO₄⁻ / HPO₄⁻ buffer:

pH = 7.2 + log [HPO₄⁻² ] / [H₂PO₄⁻]

As molarity of the dibasic phosphate is 0.2M and you want a pH of 7.4:

7.4 = 7.2 + log [0.2] / [H₂PO₄⁻]

0.2 = log [0.2] / [H₂PO₄⁻]

1.58489 = [0.2] / [H₂PO₄⁻]

[H₂PO₄⁻] = 0.1262M

<h3>The concentration of monosodium phosphate is 0.1262M</h3>

<em />

8 0
3 years ago
How many grams of NaOH would be needed to make 0.50 L of a 1.25 molar NaOH solution
Likurg_2 [28]

The solution would be made by dissolving 4 grams NaOH in .5 Liters of H2O
3 0
3 years ago
Static electricity is caused by ..
SpyIntel [72]

Answer:

ITS option B..

Explanation:

Hope it helpzz!!

7 0
2 years ago
An engineer is trying to create a fast reaction in a fuel mixture. Which should she do? A. Decrease the amount of fuel B. Lower
oksano4ka [1.4K]
To increase the rate of a reaction, you can either do any of the following:
-increase the temperature
-increase concentration of the aqueous reactant
-increase pressure of the gas
-use a catalyst
-increase surface area of the solid reactant

From these, the engineer should therefore do C. Adding a catalyst speeds up the reaction without really joining the reaction.
3 0
3 years ago
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