1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
Cloud [144]
3 years ago
6

A 5.00-mL sample of blood was treated with trichloroacetic acid to precipitate proteins. After centrifugation, the resulting sol

ution was brought to a pH of 3 and was extracted with two 5-mL portions of methyl isobutyl ketone containing the organic lead complexing agent APCD. The extract was aspirated directly into an air-acetylene flame yielding an absorbance of 0.454 at 283.3 nm. Five-milliliter aliquots of standard solutions containing 0.240 and 0.475 ppm Pb were treated in the same way and yielded absorbances of 0.412 and 0.642. Calculate the concentration Pb (ppm) in the sample assuming that Beer’s law is followed.
Chemistry
1 answer:
Anarel [89]3 years ago
3 0

Explanation:

According to the Beer-lambert' s law,

        Absrobance = absrobptitvity × lenght × concentration

So, if we will plot a graph between absrobance and concentration then we will obtain a straight line

Hence, formula to calculate slope of the graph is as follows.

   The slope of graph = \frac{\text{difference in absrobance at two points}}{\text{difference in concentrations at those points}}

The given data is as follows.

     A_{1} = 0.412 (first point)

     A_{2} = 0.642 (second point)

     C_{1} = 0.240 ppm (first point)

     C_{2} = 0.475 ppm (second point)

Hence, putting these values into the above formula we will calculate the value of slope as follows.

           Slope = \frac{\text{difference in absrobance at two points}}{\text{difference in concentrations at those points}}

                     = \frac{0.642 - 0.412}{0.475 - 0.240}

                      = \frac{0.23}{0.235}

                     = 0.978

It is known that for the graph, line equation can be written as follows.

                       y = mx + c  ........... (1)

where,      C = intercept

                 m = slope

Hence, calculate the value of intercept as follows.

           0.412 = 0.24 \times 0.978 + c

               c = 0.178

As it is given that the absorbance values 0.454 (the y-axis value). Therefore, putting this value into equation (1) we get the following.

                     y = mx + c

                  0.454 = x \times 0.978 + 0.178

                   0.276 = 0.978x

                         x = 0.282 ppm

Thus, we can conclude that the concentration of Pb in the given sample is 0.282 ppm.

You might be interested in
What is the mass in grams of a pure iron cube that has a volume of 4.60 cm3
yuradex [85]
In order to determine the mass of a substance given the volume, we require the density. The density of iron is 7.87 grams/cm³

Now,

Density = mass / volume

Mass = density * volume

Mass = 7.87 * 4.6

36.2 grams of iron are present in the cube
5 0
3 years ago
Los materiales sinteticos tienen implicaciones en el medio ambiente​
svp [43]

Answer:

no

Explanation:

los materiales sinteticos son aquellos materiales q estan hechos de polimeros sintetilizados o de pequeñas moleculas

6 0
3 years ago
Be sure to answer all parts. Consider the reaction A + B → Products From the following data obtained at a certain temperature, d
worty [1.4K]

Answer : The order of reaction with respect to A is, first order reaction.

The order of reaction with respect to B is, zero order reaction.

The overall order of reaction is, first order reaction.  

Explanation :

Rate law is defined as the expression which expresses the rate of the reaction in terms of molar concentration of the reactants with each term raised to the power their stoichiometric coefficient of that reactant in the balanced chemical equation.

For the given chemical equation:

A+B\rightarrow Products

Rate law expression for the reaction:

\text{Rate}=k[A]^a[B]^b

where,

a = order with respect to A

b = order with respect to B

Expression for rate law for first observation:

3.20\times 10^{-1}=k(1.50)^a(1.50)^b ....(1)

Expression for rate law for second observation:

3.20\times 10^{-1}=k(1.50)^a(2.50)^b ....(2)

Expression for rate law for third observation:

6.40\times 10^{-1}=k(3.00)^a(1.50)^b ....(3)

Dividing 1 from 2, we get:

\frac{3.20\times 10^{-1}}{3.20\times 10^{-1}}=\frac{k(1.50)^a(2.50)^b}{k(1.50)^a(1.50)^b}\\\\1=1.66^b\\b=0

Dividing 1 from 3, we get:

\frac{6.40\times 10^{-1}}{3.20\times 10^{-1}}=\frac{k(3.00)^a(1.50)^b}{k(1.50)^a(1.50)^b}\\\\2=2^a\\a=1

Thus, the rate law becomes:

\text{Rate}=k[A]^1[B]^0

\text{Rate}=k[A]

Thus,

The order of reaction with respect to A is, first order reaction.

The order of reaction with respect to B is, zero order reaction.

The overall order of reaction is, first order reaction.

7 0
3 years ago
If we wanted to add to the Venn diagram to reflect the Arrhenius acid-base theory, which statements would be MOST appropriate? A
Arlecino [84]

Answer:b

Explanation:

4 0
3 years ago
DUPLICATE. The half-equivalence point of a titration occurs half way to the end point, where half of the analyte has reacted to
Law Incorporation [45]
At the half equivalence point [HA] = [A-] and pH = pKa 

<span>if Ka is 5.2e-5 then pKa = pH = 4.28</span>
5 0
3 years ago
Other questions:
  • Based on the kinetic molecular theory (KMT), which statement is true?
    15·1 answer
  • Any mixture that is heterogeneous on a microscopic level is a
    10·1 answer
  • Which element is most reactive and why?<br>Fe<br>Mg<br>Pb<br>Zn​
    11·1 answer
  • (i need help please ill give brainliest if u get it right)* the questions and everything are in the picture below*
    14·1 answer
  • What substance is most soluable at 0°C​
    9·1 answer
  • Explain how particles transfer with radiation
    12·1 answer
  • Long scratch marks that are left behind as evidence of glaciers are called
    11·1 answer
  • Zn + 2HCI -&gt; ZnCl2 + H2
    11·1 answer
  • Pl help it’s for a grade I will give you Brainly
    12·1 answer
  • Convert these pressures:
    14·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!