Centi- (symbol c) is a unit prefix in the metric system denoting a factor of one hundredth.
We can solve this without a concrete formula through dimensional analysis. This works by manipulating the units such that you end up with the unit of the final answer. Manipulate them by cancelling units that appear both in the numerator and denominator side. As a result, we must be left with the units of g. The current in A or amperes is equivalent to amount of Coulombs per second. Since this involves Coulombs, we will use the Faraday's constant which is 96,500 C/mol electron. The reaction is:
Cr³⁺(aq) + 3e⁻ --> Cr(s)
This means that for every 3 moles of electron transferred, 1 mole of Chromium metal is plated. The molar mass of Cr: 52 g/mol. The solution is as follows:
Mass of Chromium metal = (8 C/s)(60 s/1 min)(160 min)(1 mol e⁻/96,500 C)(1 mol Cr/3 mol e)(52 g/mol)
<em>Mass of Chromium metal = 13.79 g</em>
Answer:
0.00268 M
Explanation:
To find the new molarity, you need to (1) find the moles of CuSO₄ (via the molarity equation using the beginning molarity and volume) and then (2) find the new molarity (using the moles and combined volume). Your final answer should have 3 sig figs to match the given values.
<u>Step 1:</u>
3.00 mL / 1,000 = 0.00300 L
Molarity = moles / volume (L)
0.0250 M = moles / 0.00300 L
(0.0250 M) x (0.00300 L) = moles
7.50 x 10⁻⁵ = moles
<u>Step 2:</u>
25.0 mL / 1,000 = 0.0250 L
0.0250 L + 0.00300 L = 0.0280 L
Molarity = moles / volume (L)
Molarity = (7.50 x 10⁻⁵ moles) / (0.0280 L)
Molarity = 0.00268 M
Problem One
<em><u>Formula</u></em>
N(t) = No * (1/2)^[t/t_1/2]
<em><u>Givens</u></em>
N(t) = the current mass of the sample = 2.10 grams
No = The original mass of the sample = No [We're trying to find this].
t = time elapsed which is 2.6 billion years or 2.6 * 10^9 years.
t1/2 = the 1/2 life time which is 1.3 billion years of 1.3 *10^9
<em><u>Solution</u></em>
2.10 grams = No (1/2)^(2.6*10^9/1.3 * 10^9)
The 10^9s cancel and you are left with 2.6/1.3 = 2
2.10 grams = No (1/2)^2
2.10 grams = No (1/4) Multiply both sides by 4
2.10 * 4 = No (1/4)*4
8.4 grams = No
which is how many grams you originally had.
Answer B.
Problem Two
Solve for y
2 + 2 = y + 1
4 = y + 1
y = 3
Solve for z
1 + 1 = z + 0
z = 2
The 2 tells you that it is the second member on the periodic table. That's Helium. So the answer looks like this.
The mass of the Helium is 3 and its number is two.
