The calculated pH of the solutions are given below:
- The pH of the solution after 14.0 ml of base is added to it is calculated as 1.45.
- The pH of the solution after 19.8 ml of base is added to it is calculated as 3.0
- The pH of the solution after 20.0 ml of base is added to it is calculated as 7.
<h3>What is pH?</h3>
This is the level of acidity or alkalinity of an aqueous solution. The pH of a substances tells if its an acid, base or neutral.
HBr and NaOH while in water would dissociate and they would become H+ and OH- respectively.
Mol of HBr = Mol * Vol
= 0.200 * 20mL
= 4 mmol
A. Moles of NaOH added
= 0.2 X 14
= 2.8 mmol
Moles of H+ that did not react
= 4 - 2.8
= 1.2 mmol
1.2/1000 = 0.0012 moles
Total volume = 20 + 14
= 34 mL to litres
= 0.034 L
Molarity of H+ = 0.0012 / 0.034L
= 0.035 M
-log[0.035] = 1.45
The pH of the solution is 1.45
B. NaOH added = 19.8 * 0.2 =
3.96 mmoles
The unreacted solution
= 4.0 - 3.96
= 0.04 mmol
0.04/1000 = 0.00004 moles
Total volume = 20 + 19.8
= 39.8mL
Converted to litres = 0.0398L
Molarity = 0.00004 / 0.0398L
= 0.001
-log(0.001) = 3.0
The ph Is therefore 3.0
C. Moles of NaOH added = 0.2*20mL = 4mmol
All the H+ are going to be consumed here. This would result into a neutral solution pH = 7
<u>Complete question:</u>
20.0 mL sample of 0.200 M HBr solution is titrated with 0.200 M NaOH solution. Calculate the PH of the solution after the following volumes of base have been added.
A. 14.0 mL
B. 19.8 mL
C. 20.0 mL
Read more on pH here; brainly.com/question/22390063
The combination that could be the total sales would be 360 tablets and 180 computers.
<h3>Total sales</h3>
Over 300 total sales were made in January
100 tablets and 20 computers were sold in February.
This means that total sales would be: (300+) 100 + 20 = 420+
Only options B and C have 420+ total sales.
But, there are more tablet sales than computers.
Thus, we are left with only option B
More on total sales can be found here: brainly.com/question/14119360
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Answer:
9/5
Explanation:
First we took the variables at one side then just solves it....
The ability to generalize a study's results to different circumstances is known as external validity that suffers from 7 types of threats.
<h3>What are the threats to External Validity?</h3>
There are 7 major threats to external validity.
- The first threat is sampling bias, in which a sample is not representative of the population.
- The second threat is history, where an unrelated incident can affect the results.
- The third threat is observer bias, in which the traits or actions of the experimenter unintentionally affect the results, resulting in bias and other demand features.
- The fourth threat is the Hawthorne effect, which describes the propensity for individuals to alter their behaviour merely because they are aware that they are being observed.
- The fifth threat is the Testing Effect, in which the results are impacted by whether a test is administered before or after another.
- The sixth threat is the aptitude-treatment, which involves the interaction of individual and group factors to affect the dependent variable.
- The environment, time of day, location, researcher traits, and other variables that restrict the generalizability of the results are included in the seventh threat.
To learn more about external validity, refer:
brainly.com/question/28760166
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