Answer:
10.10
Explanation:
Step 1: Write the basic dissociation reaction for pyridine
C₅H₅N(aq) + H₂O(l) ⇌ C₅H₅NH⁺(aq) + OH⁻(aq) Kb = 1.9 × 10⁻⁹
Step 2: Calculate [OH⁻]
For a weak base, we will use the following expression.
[OH⁻] = √(Cb × Kb) = √(9.2 × 1.9 × 10⁻⁹) = 1.3 × 10⁻⁴ M
Step 3: Calculate pOH
We will use the definition of pOH.
pOH = -log [OH⁻] = -log 1.3 × 10⁻⁴ = 3.9
Step 4: Calculate pH
We will use the following expression.
pH = 14 - pOH = 14 - 3.9 = 10.10
A mole of water molecules contains 2 moles of hydrogen atoms and 1 mole of oxygen atoms.
The thid choice (from left to right) is a Ball and Stick Model.
Answer:
Hg
Explanation:
We are given information about the unknown element, and using each characteristic, we can narrow down the possible elements until we have just one possibility left.
Conducts electricity: This means that the element has to be a metal, or a semi-metal, because non-metals cannot conduct electricity.
Forming chloride and oxide ions: When it is seen that it forms chloride and oxide ions in the form of XCl₂ and XO, it can be seen that this element has an ionic charge of +2. This narrows it down to the elements in <u>Group 2.</u>
Liquid at room temperature: This is tricky, because we realize that there are no elements in group 2 that are liquid at room temperature. So hence we can look at groups 3 to 12, and see if there are any liquid metals with an ionic charge of +2.
Taking all this information into account, we can see that the only element it can be is mercury (Hg).
