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3 years ago

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Which is the BEST evidence that a chemical change has occurred?

1 answer:

MaRussiya [10]3 years ago

3 0

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there is an ice cream shop 6 blocks north of your hotel. how many minutes will it take to walk there and back

Allushta [10]

Answer:

This question is incomplete

Explanation:

This question is incomplete.

However, when all the required data are available, you can use the formula/steps below

Average speed/velocity (m/s) = distance (in metres) ÷ time (in seconds)

Time (in secs) = distance ÷ average speed/velocity

Kindly note that "blocks" is not a standard unit for distance measurement in science, hence the distance (since its a walking distance) must be in metres (or converted to metres if not in metres).

The distance in the formula is the distance from the hotel to the ice cream shop while the average speed is the distance covered per time as s/he walks to the ice cream shop and back. Hence, the answer gotten from the formula above will have to be multiplied by 2 (in order to get the time taken to walk to the ice cream shop and back) because the formula will only provide answer to one trip (time taken to walk to the shop).

After the multiplication mentioned above, the time in seconds should be converted to minutes by dividing the answer in seconds by 60

8 0

3 years ago

In a pendulum, a continuous change occurs between kinetic energy and

Masja [62]

It should be potential energy!!!

7 0

3 years ago

How did modern scientists experiment with Van Gogh's paints to determine their chemical reactions?

Andrei [34K]

Answer:

I think the answer is A - they used X-ray analysis.

Explanation:

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3 years ago

Read 2 more answers

Which of the following is not an example of a chemical change?

elena55 [62]

This would be C. A car rusting

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3 years ago

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Assuming the volumes are additive, what is the [Cl−] in a solution obtained by mixing 297 mL of 0.675 M KCl and 664 mL of 0.338

Elden [556K]

<u>Answer:</u> The concentration of chloride ions in the solution obtained is 0.674 M

<u>Explanation:</u>

To calculate the number of moles for given molarity, we use the equation:

$\text{Molarity of the solution}=\frac{\text{Moles of solute}\times 1000}{\text{Volume of solution (in mL)}}$ .....(1)

<u>For KCl:</u>

Molarity of KCl solution = 0.675 M

Volume of solution = 297 mL

Putting values in equation 1, we get:

$0.675=\frac{\text{Moles of KCl}\times 1000}{297}\\\\\text{Moles of KCl}=\frac{(0.675mol/L\times 297)}{1000}=0.200mol$

1 mole of KCl produces 1 mole of chloride ions and 1 mole of potassium ion

Moles of chloride ions in KCl = 0.200 moles

<u>For magnesium chloride:</u>

Molarity of magnesium chloride solution = 0.338 M

Volume of solution = 664 mL

Putting values in equation 1, we get:

$0.338=\frac{\text{Moles of }MgCl_2\times 1000}{664}\\\\\text{Moles of }MgCl_2=\frac{(0.338mol/L\times 664)}{1000}=0.224mol$

1 mole of magnesium chloride produces 2 moles of chloride ions and 1 mole of magnesium ion

Moles of chloride ions in magnesium chloride = $(2\times 0.224)=0.448mol$

Calculating the chloride ion concentration, we use equation 1:

Total moles of chloride ions in the solution = (0.200 + 0.448) moles = 0.648 moles

Total volume of the solution = (297 + 664) mL = 961 mL

Putting values in equation 1, we get:

$\text{Concentration of chloride ions}=\frac{0.648mol\times 1000}{961}\\\\\text{Concentration of chloride ions}=0.674M$

Hence, the concentration of chloride ions in the solution obtained is 0.674 M

5 0

3 years ago