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
irinina [24]
3 years ago
14

Atomic absorption spectroscopy was used to determine the amount of aluminum in a sample of sunscreen. A blank solution was measu

red seven times to determine the detection and quantitation limits of the spectrometer. The blank readings were: 0.0159 , 0.0081 , 0.0095 , 0.0109 , 0.0090 , 0.0114 , and 0.0090 AU. Determine the signal at the detection limit and the signal at the limit of quantitation for this method.
Chemistry
1 answer:
Pepsi [2]3 years ago
3 0

Answer:

LOD = 0,0177

LOQ = 0,0345

Explanation:

Detection limit (LOD) is defined as the lowest signal which, with a stated probability, can be distinguished from a suitable blank signal. In the same way, quantification limit (LOQ) is defined as the lowest analyte concentration that can be quantitatively detected with a stated accuracy and precision.

There are many formulas but the most used are:

LOD = X + 3σ

LOQ = X + 10σ

Where X is average and σ is standard desvation

For the blanks readings the average X is 0,0105 and σ is 0,0024

Thus:

<em>LOD = 0,0177</em>

<em>LOQ = 0,0345</em>

I hope it helps!

You might be interested in
Josh drives her scooter 7 km north. she stops for lunch and then drives 5 km east. what distance does she cover? what was her di
weqwewe [10]

Explanation:

Find the motion diagram attached for the illustration:

Distance is the length of path traveled from the start to the finish. In measuring distance, we wall through the path from start to the finishing point. Distance is a scalar magnitude that has magnitude but no direction.

Displacement is distance that is taken between the start and finishing point. It is a vector quantity that has magnitude and measures direction.

To find the distance;

Distance = 5km + 7km = 12km

Displacement:

 Using pythagoras theorem;

   Displacement = √7² + 5² = 8.6km

 Direction:

    sin(bearing ) = \frac{5}{8.6}  = 0.5814

   bearing = arcSin 0.5814 = 035.6°

Displacement is 8.6km in a direction 035.6°

learn more:

Displacement brainly.com/question/6123316

#learnwithBrainly

6 0
2 years ago
Why using a temperature probe is preferable to using a conventional mercury thermometers
Crank
This for health and hazard purposes. The conventional thermometers contain mercury which is very dangerous to health. It is toxic which could cause poisoning, respiratory damage and kidney problems. Because of this, it is already illegal to use them for safety purposes. Temperature probes are much safer because they only use thermocouples.
3 0
2 years ago
Calculate the pH of a solution that contains 2.7 M HF and 2.7 M HOC6H5. Also, calculate the concentration of OC6H5- in this solu
borishaifa [10]

Answer:

\large \boxed{\mathbf{1.36; 3.6 \times 10^{\mathbf{-9}}}\textbf{mol/L}}

Explanation:

The HF is about five million times as strong as phenol, so it will be by far the major contributor of hydronium ions. We can ignore the contribution from the phenol.

1 .Calculate the hydronium ion concentration

We can use an ICE table to organize the calculations.

                    HF + H₂O ⇌ H₃O⁺ + F⁻

I/mol·L⁻¹:       2.7                   0       0

C/mol·L⁻¹:      -x                   +x      +x

E/mol·L⁻¹:   2.7 - x                 x        x

K_{\text{a}} = \dfrac{\text{[H}_{3}\text{O}^{+}] \text{F}^{-}]} {\text{[HF]}} = 7.2 \times 10^{-4}\\\\\dfrac{x^{2}}{2.7 - x} = 7.2 \times 10^{-4}\\\\\text{Check for negligibility of }x\\\\\dfrac{2.7}{7.2 \times 10^{-4}} = 4000 > 400\\\\\therefore x \ll 2.7\\\dfrac{x^{2}}{2.7} = 7.2 \times 10^{-4}\\\\x^{2} = 2.7 \times 7.2 \times 10^{-4} = 1.94 \times 10^{-3}\\x = 0.0441\\\text{[H$_{3}$O$^{+}$]}= \text{x mol$\cdot$L$^{-1}$} = \text{0.0441 mol$\cdot$L$^{-1}$}

2. Calculate the pH

\text{pH} = -\log{\rm[H_{3}O^{+}]} = -\log{0.0441} = \large \boxed{\mathbf{1.36}}

3. Calculate [C₆H₅O⁻]

C₆H₅OH + H₂O ⇌ C₆H₅O⁻ + H₃O⁺

     2.7                         x        0.0441

K_{\text{a}} = \dfrac{0.0441x} {2.7} = 1.6 \times 10^{-10}\\\\0.0441x = 1.6 \times 10^{-10}\\x = \dfrac{1.6 \times 10^{-10}}{0.0441} = \mathbf{3.6 \times 10^{\mathbf{-9}}}\textbf{ mol/L}\\\text{The concentration of phenoxide ion is $\large \boxed{\mathbf{3.6 \times 10^{\mathbf{-9}}}\textbf{ mol/L}}$}

6 0
3 years ago
Is this correct? please check
Reil [10]

Answer:

A is the correct option

Explanation:

batteries have chemical energy and will convert to electricity and when reached to bulb, it emits light as electromagnetic rays

4 0
2 years ago
The equilibrium for the reaction between (ch3)2nh a weak base
nadezda [96]

The equilibrium for the dissolution of the weak base is ;(CH3)2NH(aq) + H2O(l) ⇄ (CH3)2NH3^+(aq) + OH^-(aq)

<h3>What is a weak base?</h3>

A weak base is one that does not ionize completely in solution. As such, a weak base will have a very low base dissociation constant Kb reflecting its minimal dissociation in solution.

The question is incomplete hence we are are unable to work out the equilibrium but in solution it will look like this;

(CH3)2NH(aq) + H2O(l) ⇄ (CH3)2NH3^+(aq) + OH^-(aq)

Learn more about weak base: brainly.com/question/4131966

7 0
2 years ago
Other questions:
  • Is NaF an acid, base or salt?
    8·2 answers
  • A student would like to determine how heating a liquid changes its volume. The student hypothesizes that the liquid will increas
    15·1 answer
  • Explain the order of entropy of particles in the states of matter.
    13·1 answer
  • Hunter wants to measure the weight of a dumbbell. He should
    5·1 answer
  • What two ways do nuclear power reactors harm the enviornment
    8·1 answer
  • True or false, rewrite it to make it true.
    14·1 answer
  • What would you expect to observe when Br2 reacts with 2-butyne?
    14·1 answer
  • Order these by size/complexity in descending order. (largest/most complex on top) Reorder answers
    12·1 answer
  • I'm asking again because the other one I did won't show up. Also please explain! Thanks! :)
    13·2 answers
  • Helium only has two valence electrons and is a stable atom. How is this possible when atoms
    12·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!