Answer:
e. When the indicator changes color and remains, 2 more drops of the solution in the buret should be added.
Explanation:
<em>Which statement is incorrect?
</em>
<em>Select one:
</em>
<em>
a. The volume of solution in the buret should be recorded when the endpoint is reached.
</em> CORRECT. At the endpoint, the titrant is expected to have completely reacted with the titrand.
<em>b. It is good practice to place the flask over a white background to better observe the color change of the solution.</em> CORRECT. Using a white background makes it easier to detect the changes in the color of the indicator.
<em>c. The endpoint is when the indicator changes color.</em>
CORRECT. This is the function of an indicator.
<em>d. Phenolphthalein will go from a colorless solution to a pink solution for the addition of NaOH to an acid solution.</em> CORRECT. Phenolphthalein is colorless when pH < 8.3 and it is pink when pH > 10.0.
<em>e. When the indicator changes color and remains, 2 more drops of the solution in the buret should be added.</em> INCORRECT. When the endpoint is reached, no more titrant should be added.
Answer:
2.0 atoms of K and 1.0 atom of S are needed to form a molecule of potassium sulfide.
Explanation:
- The potassium sulfide has the chemical formula <em>K₂S.</em>
∴ Every 1.0 molecule of K₂S composed of 2.0 atom of K and 1.0 atoms of S.
<u><em>So, 2.0 atoms of K and 1.0 atom of S are needed to form a molecule of potassium sulfide.</em></u>
Answer:
81 molecules
Explanation:
The reaction between C5H12 and O2 is a combustion reaction and is represented by the following equation;
C5H12 + 8O2 --> 5CO2 + 6H2O
The ratio of C5H12 to O2 from the above equation is 1 : 8.
Aplying the conditins of the question; 24 molecules each of C5H12 and O2 we have;
3C5H12 + 24O2 --> 15CO2 + 18H2O
This means we have 24 - 3 = 21 molecules of C5H12 that are unreacted.
Total molecules is given as;
3(C5H12) + 24(O2) + 15(CO2) + 18(H2O) + 21(Unreacted C5H12) = 81 molecules
Answer:
D
Explanation:
i took the test and got it right :)