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2 quick chemistry questions


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Huh? Sorry, I don't understand... please clarify.

 

Water is a polar aqueous solvent. It dissolves polar compounds.

Acetone is a polar organic solvent. It is more hydrophobic than water, and therefore can dissolve more hydrophobic compounds like plastic.

 

It seems to me that you are perhaps unclear on what a solvent is... do you have a general chemistry textbook handy?

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What is the heterogeneous mixture? A heterogenous mixture just means a mixture of multiple things that is not consistent in composition throughout.

 

When you say "left over material", where has the other part of the material gone?

 

Be careful with the words "bond" and "bind. Solvents "interact" via "intermolecular forces" to dissolve things.

 

EDIT: Alright, I can't stay up any longer. I've got class in 8 hours, so it's time to sleep. Hopefully someone else can help you. Good luck!

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Might as well continue this as the random homework question thread... I've been trying this particular physics question and have yet to find the correct answer and honestly it is driving me insane...Nobody I have consulted with in my lecture has the answer yet. So I challenge you to help me understand how to answer this:

 

A sprinter can accelerate with constant acceleration for 3.70 before reaching top speed. He can run the 100-meter dash in 10 s. What is his speed as he crosses the finish line?

 

My thinking is that this question needs to be split into two parts: 1) constant acceleration 2) Constant velocity. For part 1) we know: x-initial=0m, x-final=unknown,v-initial=0m/s,v-final=unknown,acceleration=unknown and time=3.7seconds.

 

For part 2) we know x-initial=xfinal from part 1),x-final=100m,v-initial=v-final from part 1),v-final=unknown, no acceleration, time is equal to 6.3 sec.

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Might as well continue this as the random homework question thread... I've been trying this particular physics question and have yet to find the correct answer and honestly it is driving me insane...Nobody I have consulted with in my lecture has the answer yet. So I challenge you to help me understand how to answer this:

 

A sprinter can accelerate with constant acceleration for 3.70 before reaching top speed. He can run the 100-meter dash in 10 s. What is his speed as he crosses the finish line?

 

My thinking is that this question needs to be split into two parts: 1) constant acceleration 2) Constant velocity. For part 1) we know: x-initial=0m, x-final=unknown,v-initial=0m/s,v-final=unknown,acceleration=unknown and time=3.7seconds.

 

For part 2) we know x-initial=xfinal from part 1),x-final=100m,v-initial=v-final from part 1),v-final=unknown, no acceleration, time is equal to 6.3 sec.

 

You're right - you need to split the question into 2 parts. What unifies the two parts of the question is that total distance is 100 m.

 

1. Distance covered while the runner is accelerating = A. Time spent in A = t.

Use the equation:

d = vᵢt + ½at² = ½at² since vᵢ is 0

 

2. Distance covered when the runner has reached top speed = B. Time spent in B = T.

Use the equation:

d = vT

 

Put those two equations together. A + B = 100.

100 = ½at² + vT

100 = ½a(3.7)² + v(6.3)

100 = 6.85a + 6.3v

 

You end up with 2 variables. Acceleration, a. Final speed, v.

 

You know that v = vᵢ + at. Since vᵢ is 0...

v = at = 3.7a

a = v/3.7

 

Put that back into your equation.

100 = 6.85a + 6.3v

100 = 6.85(v/3.7) + 6.3v

100 = 8.15v

v = 12.3 m/s

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