Answer:
Ions are formed when atoms lose or gain electrons in order to fulfill the octet rule and have full outer valence electron shells. When they lose electrons, they become positively charged and are named cations. When they gain electrons, they are negatively charged and are named anions.
Explanation:
Answer: 72.41% and 26.90% respectively.
Explanation:
At 60°C, you can dissolve 46.4g of acetanilide in 100mL of ethanol. If you lower the temperature, at 0°C, you can dissolve just 12.8g, which means (46.4g-12.8g)=33.6g of acetanilide must have precipitated from the solution.
We can calculate recovery as:

So the answer to the first question is 72.41%.
For the second part just use the same formula, the mass of the precipitate is the final mass minus the initial mass, (171mg-125mg)=46mg.

So the answer to the second question is 26.90%.
Answer:
pH = 11.3
Explanation:
From the question given above, the following data were obtained:
Concentration of hydronium ion [H₃O⁺] = 4.950×10¯¹² M
pH =.?
The pH of a solution is defined by the following equation:
pH = –Log [H₃O⁺]
Thus, with the above formula, we can obtain the pH of the solution as follow:
Concentration of hydronium ion [H₃O⁺] = 4.950×10¯¹² M
pH =.?
pH = –Log [H₃O⁺]
pH = –Log 4.950×10¯¹²
pH = 11.3
The tool to measure the liquid is a measuring cylinder.