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3 years ago

In a chemical reaction, energy can be A. released. B. absorbed. C. released or absorbed. D. neither released nor absorbed.

2 answers:

4 0

C. released or absorbed.

When the energy is released the reaction is called exotermic reaction
When the energy is absorbed, the reaction is called endothermic reaction

An example of exotermic reaction is between water and H2SO4

USPshnik [31]3 years ago

4 0

Oof I was about to say the same answer.

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What is the molarity of an H3PO4solution if 15.0 mL is completely neutralized by 38.5 mL of 0.150 MNaOH? Please explain your ans

rodikova [14]

Answer:

M=Molarity

V=volume

change millilitre to litre

so:15ml=0.015 L

:38.5ml=0.0385 L

M1V1=M1V1

M1* 0.015 L= 0.15M*0.0385 L

M1=0.00385

8 0

3 years ago

Calculate the change in energy when 75.0 grams of water drops from<br> 31.0C to 21.6.

zysi [14]

Answer: Step 1: Calculate qsur (the surrounding is

usually the water)

qsur = ? J

m = 75.0 g water

c = 4.184 J/g

ΔT = (Tfinal- Tinitial)= (21.6 – 31.0) = -9.4 oC

qsur = m · c · (ΔT)

qsur = (75.0g) (4.184 J/g

oC) (-9.4 oC)

qsur = - 2949.72 J

First, using the information we know that we

must solve for qsur, which is the water. We know

the mass for water, 75.0g, the specific heat of

the water, 4.184 j/g

c, and the change in

temperature, 21.6-31.0 = -9.4 oC. Plugging it

into the equation, we solve for qsur.

Step 2: Calculate qsys qsys = - (qsur)

qsys = - (- 2949.72 J)

qsys = + 2949.72

In this case, the qsur is negative, which means

that the water lost energy. Where did it go? It

went to the system. Thus, the energy of the

system is negative, opposite, the energy of the

surrounding.

Step 3: Calculate moles of the substance

that is the system

Given: 12.8 g KCl

Mol system = (g system given)

(molar mass of system)

Mol system = (12.8 g KCl)

(39.10g + 35.45g)

Mol system = 12.8 g KCl

74.55 g

Mol system = 0.172

Here, we solve for the mol in the system by

using the molar mass of the material in the

system.

Step 4: Calculate ΔH ΔH = q sys .

Mol system

ΔH= + 2949.72 J

0.172 mol

ΔH= +17179.81 J/mol or +1.72 x 104

J/mol

i hope this helps

5 0

3 years ago

Read 2 more answers

I typed a question. It said give points. I selected. Someone answered notification came. But where do I see they persons answer?

Ksivusya [100]

Answer:

212.304 grams

Explanation:

similar to your other question, use the same formula

q=mCpΔT

23617=m(4.182)(46.6-20)

23617=111.2412m

m=212.304g

6 0

2 years ago

Is magnetism, reactivity, and fluorescence used to identify minerals

valkas [14]

Yes it is used , hope this helps

6 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:

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