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damaskus [11]
3 years ago
6

In this experiment, a calibration curve, often called a Beer's Law plot, will be made. A calibration curve should have which of

the following attributes? (Select all that apply.)A. Absorbance is plotted on the x-axis.B. Concentration is plotted on the x-axis.C. The x- and y-axes should be labeled with units as well as quantities.D. Concentration is plotted on the y-axis.E. In a hand-plotted graph, individual lines should be drawn between adjacent points.F. Absorbance is plotted on the y-axis.G. The command for getting an equation is "Add Trendline" in Microsoft Excel.
Chemistry
1 answer:
mr_godi [17]3 years ago
6 0

Answer:

B, C  and F are true, see explanation below.

Explanation:

Beer´s law is given by the formula:

A = εcl,  where   A = Absorbance,

                           ε = molar extinction coefficient,

                           c = concentration in mol/L (M), and

                           l = path length of the cuvette containing the sample,

                               

Now the usefulness of this relation is that if we plot the Absorbance vs  concentration, we get a straight line since the Beer equation has the form  y = mx + b.After the slope and y intercept have been determined, we can determine an unknow concentration of the substance by measuring its absorbance.

This relation is valid for low concentration, and  there are deviations from it.

We are now ready to answer this question with this brief introduction:

A. Absorbance is plotted on the x-axis

False, we plot the absorbance in the y-axis.

B. Concentration is plotted on the x-axis.

True, we vary the concentration and read the absorbance so the plot is Absorbance vs Concentration.

C. The x- and y-axes should be labeled with units as well as quantities

This is true for our plot to be useful and correct.

D. Concentration is plotted on the y-axis

False, for all the reasons stated above.

E. In a hand-plotted graph, individual lines should be drawn between adjacent points

False, in a hand plotted graph we will pass the line between all the points determined as close as to produce the best line where we can read values for the absorbance for a given concentration.

F. Absorbance is plotted on the y-axis

True

G. The command for getting an equation is "Add Trendline" in Microsoft Excel.

False, the command adds only the line of the best fit to our data, to get the equation of the line we have to specify it by choosing it in the options for the format of trendline.

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In which of the following compounds does the carbonyl stretch in the IR spectrum occur at the lowest wavenumber?
klio [65]

Answer:

a. Cyclohexanone

Explanation:

The principle of IR technique is based on the <u>vibration of the bonds</u> by using the energy that is in this region of the electromagnetic spectrum. For each bond, there is <em>a specific energy that generates a specific vibration</em>. In this case, you want to study the vibration that is given in the carbonyl group C=O. Which is located around 1700 cm-1.

Now, we must remember that the <u>lower the wavenumber we will have less energy</u>. So, what we should look for in these molecules, is a carbonyl group in which less energy is needed to vibrate since we look for the molecule with a smaller wavenumber.

If we look at the structure of all the molecules we will find that in the last three we have <u>heteroatoms</u> (atoms different to carbon I hydrogen) on the right side of the carbonyl group. These atoms allow the production of <u>resonance structures</u> which makes the molecule more stable. If the molecule is more stable we will need more energy to make it vibrate and therefore greater wavenumbers.

The molecule that fulfills this condition is the <u>cyclohexanone.</u>

See figure 1

I hope it helps!

4 0
3 years ago
How many grams of solid NaOH are required to prepare a 400ml of a 5N solution? show your work!
Nuetrik [128]

<u>Answer:</u> The mass of solid NaOH required is 80 g

<u>Explanation:</u>

Equivalent weight is calculated by dividing the molecular weight by n factor. The equation used is:

\text{Equivalent weight}=\frac{\text{Molecular weight}}{n}

where,

n = acidity for bases = 1 (For NaOH)

Molar mass of NaOH = 40 g/mol

Putting values in above equation, we get:

\text{Equivalent weight}=\frac{40g/mol}{1eq/mol}=40g/eq

Normality is defined as the umber of gram equivalents dissolved per liter of the solution.

Mathematically,

\text{Normality of solution}=\frac{\text{Number of gram equivalents} \times 1000}{\text{Volume of solution (in mL)}}

Or,

\text{Normality of solution}=\frac{\text{Given mass}\times 1000}{\text{Equivalent mass}\times \text{Volume of solution (in mL)}}         ......(1)

We are given:

Given mass of NaOH = ?

Equivalent mass of NaOH = 40 g/eq

Volume of solution = 400 mL

Normality of solution = 5 eq/L

Putting values in equation 1, we get:

5eq/L=\frac{\text{Mass of NaOH}\times 1000}{40g/eq\times 400mL}\\\\\text{Mass of NaOH}=80g

Hence, the mass of solid NaOH required is 80 g

4 0
3 years ago
Provide a definition of a closed system.
tensa zangetsu [6.8K]

Answer:

A closed system is a physical system that does not allow transfer of matter in or out of the system, though, in different contexts, such as physics, chemistry or engineering, the transfer of energy is or is not allowed.

Explanation:

5 0
2 years ago
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Pachacha [2.7K]
1/16 ( ignore this the stupid website just makes us use 20 characters UGH! )
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2 years ago
What is the formula for triboron silicide?
artcher [175]

Answer:

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Explanation:

Let's take  break it down. From triboron silicide;

Tri - Three

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Silicide - Silicon (with an -ide suffix)

The formular is given as;

B₃Si

7 0
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