Answer:
strength = 10⁻²/10⁻³ = 10 times more acidic
Explanation:
1. A solution with a pH of 9 has a pOH of
pH + pOH = 14 => pOH = 14 - pH = 14 - 9 = 5
2. Which is more acidic, a solution with a pH of 6 or a pH of 4?
pH of 4 => Higher [H⁺] = 10⁻⁴M vs pH of 6 => [H⁺] = 10⁻⁶M
3. How many times more acidic is a solution with a pH of 2 than a solution with a pH of 3?
soln with pH = 2 => [H⁺] = 10⁻²M
soln with pH = 3 => [H⁺] = 10⁻³M
strength = 10⁻²/10⁻³ = 10 times more acidic
4. What is the hydrogen ion concentration [H + ] in a solution that has a pH of 8?
[H⁺] = 10^-pH = 10⁻⁸M
5. A solution has a pOH of 9.6. What is the pH? (Use the formula.)
pH + pOH = 14 => pH = 14 - 9.6 = 4.4
Answer:
320 g
Step-by-step explanation:
The half-life of Co-63 (5.3 yr) is the time it takes for half of it to decay.
After one half-life, half (50 %) of the original amount will remain.
After a second half-life, half of that amount (25 %) will remain, and so on.
We can construct a table as follows:
No. of Fraction Mass
half-lives t/yr Remaining Remaining/g
0 0 1
1 5.3 ½
2 10.6 ¼
3 15.9 ⅛ 40.0
4 21.2 ¹/₁₆
We see that 40.0 g remain after three half-lives.
This is one-eighth of the original mass.
The mass of the original sample was 8 × 40 g = 320 g
Answer:
Explanation:
The Lanthanides were first discovered in 1787 when a unusual black mineral was found in Ytterby, Sweden. This mineral, now known as Gadolinite, was later separated into the various Lanthanide elements. In 1794, Professor Gadolin obtained yttria, an impure form of yttrium oxide, from the mineral.
