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3 years ago

Help please !!!

Chemistry

2 answers:

steposvetlana [31]3 years ago

6 0

I believe it’s friction transfers kinetic energy to heat

Rom4ik [11]3 years ago

6 0

Answer: A

Explanation: I hope this help:]

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Science question down below

aliya0001 [1]

Option 1/A (It is the first one)

6 0

3 years ago

A bomb calorimetric experiment was run to determine the enthalpy of combustion of ethanol. The reaction is The bomb had a heat c

gulaghasi [49]

Answer:

The enthalpy of combustion of ethanol in kJ/mol is -1419.58 kJ/mol.

Explanation:

The heat absorbed by the bomb and water is equal to the product of the heat capacity and the temperature change. Working with this equation, and assuming no heat is lost to the surroundings, we write :

qcal= Ccal × ΔT= 490 J/K × 276.7 K= <u>135,583 J</u> = 135.58 kJ

Note we expressed the temperature change in K, because the heat capacity is written in K.

<u> Now that we have the heat of combustion, we need to calculate the molar heat. </u>

Because qsystem = qrxn + qcal and qrxn = -qcal, the heat change of the reaction is -135.58 kJ.

This is the heat released by the combustion of 4.40 g of ethanol ; therefore, we can write the <u>conversion factor as 135.58 kJ/ 4.40 g</u>.

The molar mass of ethanol is 46.07 g, so the heat of combustion of 1 mole of ethanol is :

molar heat of combustion= -135.58 kJ/4.40 g x 46.07 g/ 1 mol= -1419.58 kJ/mol

Therefore, the enthalpy of combustion of ethanol in kJ/mol is -1419.58 kJ/mol.

3 0

3 years ago

You make an experiment to determine the percent mass of carbon in sugar. You find out that there is 46.63g of carbon in 75.00g o

Aleksandr [31]

Taking into account the definition of percentage composition, the percent composition of carbon in this sample is 62.17%.

<h3>Percentage composition</h3>

The Percentage Composition is a measure of the amount of mass that an element occupies in a compound and indicates the percentage by mass of each element that is part of a compound.

Then, the percentage by mass expresses the concentration and indicates the amount of mass of solute present in 100 grams of solution.

In other words, the percentage by mass of a component of the solution is defined as the ratio of the mass of the solute to the mass of the solution, expressed as a percentage.

The percentage by mass is calculated as the mass of the solute divided by the mass of the solution, the result of which is multiplied by 100 to give a percentage. This is:

$percentageby mass= \frac{mass of solute}{mass of solution}x100$

In this case, you know:

mass of solute= 46.63 g
mass of solution= 75 g

Replacing:

$percentageby mass= \frac{46.63 g}{75 g}x100$

Solving:

<u><em>percentage by mass= 62.17 %</em></u>

Finally, the percent composition of carbon in this sample is 62.17%.

Learn more about percent composition:

<u>brainly.com/question/24201923?referrer=searchResults</u>

<u>brainly.com/question/9779410?referrer=searchResults</u>

<u>brainly.com/question/17030163?referrer=searchResults</u>

3 0

2 years ago

The density of gold is 19.32 g/mL. What is the volume, in mL, of a nugget of gold with a mass of 55.07 g?

Vika [28.1K]

Answer: 2.850

Explanation:

$19.32=\frac{55.07}{v}\\19.32v=55.07\\v=\frac{55.07}{19.32}=\boxed{2.850 \text{ mL}}$

5 0

2 years ago

Suppose oxygen was much less electronegative than it is, so that hydrogen-oxygen bonds were much less polar and hydrogen bonds c

spayn [35]

Water would have a much lower boiling point much like its other hydrides and it would loss its ability to dissolve polar substances plus it couldn't form water columns so no more cohesion between water molecules

6 0

3 years ago

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