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7nadin3 [17]
3 years ago
7

5.00 g of carbon were adiabatically burned to CO2 in a 2.00 kg copper calorimeter which contained 2.50 kg of water. The temperat

ure increased by 14.1 °C.
Specific heats: copper, 0.385 J K⁻¹ g⁻¹; water, 4.184 J K⁻¹ g⁻¹.

a) Determine the heat of combustion of carbon ignoring any heat absorbed by the calorimeter.
b) Now determine the heat of combustion considering the heat absorbed by the calorimeter.
Chemistry
1 answer:
lorasvet [3.4K]3 years ago
3 0

Answer:

A. -163.96kJ

B. -158.34kJ

Explanation:

Heat of combustion is the heat released when an element with oxygen at stp.

Reaction for the combustion of carbon:

C(s) + O2(g) --> CO2(g)

Enthalpy heat of combustion, C (using Hess law) = -393.5 kJ/mol

m = 5g

Molecular weight = 12 g/mol

No of moles = mass/molecular weight

= 5/12

= 0.417mol

DH = -393.5 * 0.417

= -163.96 kJ

B. Heat absorbed by the calorimeter = heat evolve by combustion

= mCH2ODT + mCcDT

Where CH2O is the specific heat capacity of the water in the calorimeter

Cc is the specific heat capacity of copper calorimeter

= (2500*4.184*14.1) + (2000*0.385*14.1)

= -158343J

= -158.34kJ

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If 10.00 mL of the solution prepared in question 4 is used to make another 125.00 mL solution of NaCl, what is the new concentra
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The new concentration of the solution is 0.016 M

<h3>Dilution</h3>

From the question, we are to determine the concentration of the new solution prepared from question 4.

NOTE: Question is provided below

From question 4, the concentration of the sodium chloride solution is 0.200M

Now, to determine the new concentration,

Using the dilution law

C₁V₁ = C₂V₂

Where

C₁ is the initial concentration

V₁ is the initial volume

C₂ if the final concentration

and V₂ is the final volume

Then,

C₁ = 0.200 M

V₁ = 10.00 mL
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V₂ = 125.00 mL

Then,

0.200 × 10.00 = C₂ × 125.00

C_{2}= \frac{0.200 \times 10}{125.00}

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Hence, the new concentration of the solution is 0.016 M

Question 4:

Calculate the amount of solid sodium chloride needed to make 200.00 mL of a 0.200 M solution

Learn more on Dilution here: brainly.com/question/24881505

8 0
2 years ago
1. If there are 100 navy beans, 27 pinto beans and 173 blackeyed peas in a container, what is the percent abundance in the conta
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The answers to the two questions are:

1. The percent abundance in the container which has <u>100 navy</u>, <u>27 pinto</u>, and <u>173 black-eyed peas beans</u> is 33.3%, 9.0%, and 57.7% for navy bean, pinto bean, and black-eyed <em>peas </em>beans, respectively.

2. The <em>weighted </em>average score for the scores of 85, 75, 96 obtained from the evaluations of exams (20%), labs (75%), and homework (96%) is 84.1.      

1. The percent abundance by type of bean is given by:

\% = \frac{n}{n_{t}} \times 100   (1)

Where:

n: is the number of each type of beans

n_{t}: is the <em>total number</em> of <em>beans </em>

The <em>total number </em>of <em>beans</em> can be calculated by adding the number of all the types of beans:

n_{t} = n_{n} + n_{p} + n_{b}   (2)

Where:

n_{n}: is the number of navy beans = 100

n_{p}: is the number of pinto beans = 27

n_{b}: is the number of black-eyed <em>peas </em>beans = 173  

Hence, the total number of beans is (eq 2):

n_{t} = 100 + 27 + 173 = 300  

Now, the <em>percent abundance</em> by type of bean is (eq 1):

  • Navy beans

\%_{n} = \frac{100}{300} \times 100 = 33.3 \%

  • Pinto beans

\%_{p} = \frac{27}{300} \times 100 = 9.0 \%

  • Black-eyed peas beans

\%_{b} = \frac{173}{300} \times 100 = 57.7 \%

Hence, the percent abundance by type of bean is 33.3%, 9.0%, and 57.7% for navy bean, pinto bean, and black-eyed peas beans, respectively.

2. The average score (S) can be calculated as follows:

S = e*\%_{e} + l*\%_{l} + h*\%_{h}   (3)

Where:

e: is the score for exams = 85

l: is the score for lab reports = 75

h: is the score for homework = 96

%_{e}\%_{e}: is the <em>percent</em> for<em> exams</em> = 70.0%

\%_{l}: is the <em>percent </em>for <em>lab reports</em> = 20.0%

\%_{h}: is the <em>percent </em>for <em>homework </em>= 10.0%

Then, the <u>average score</u> is:

S = 85*0.70 + 75*0.20 + 96*0.10 = 84.1

We can see that if the score for each evaluation is 100, after multiplying every evaluation for its respective percent, the final average score would be 100.  

Therefore, the <em>weighted </em>average score will be 84.1.

Find more about percents here:

  • brainly.com/question/255442?referrer=searchResults
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I hope it helps you!

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Answer:

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(a simple mnemonic is RMIVUXG)

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<span>Dalton's atomic theory originally has 5 postulates. Among the choices, there are three that are included. These are:

*atoms of one element cannot change into atoms of another element.
</span><span>*each element is composed of tiny, indestructible particles called atoms.
</span><span>*atoms combine in simple, whole number ratios to form compounds

The others are incorrect. Atoms of one element cannot change to another element. Atoms of the same element do not have the same mass because they can occur as isotopes. Nuclear particles are not part of Dalton's theory, just the chemical reactions.</span>
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