So what we know:
-Atomic Mass = Protons + Neutrons
-Atomic Number is the number of protons
Magnesium's atomic number is 12, so the natural occurring isotope for magnesium is Mg-12 (12 protons and 12 neutrons). Added up we have an atomic mass of 24 amu. Which means if we added one neutron in Mg-13, our atomic mass would be 25 amu.
We can use the equation:
(amu of isotope 1)x + (amu of isotop 2)(x-1) = Average atomic mass
where isotope 1 is the fractional abundance we're solving for.
Plugged in it looks like this:
24x + 25(1-x) = 24.3
Now to solve for x:
24x + 25 - 25x = 24.3
-x + 25 = 24.3
-x = -.7
x = .7
So in this case, the fractional abundance of Mg-12 would be .7, or 70%.<span />
The
number of iron atoms in a cooking pot that has a mass of 0.500 kg can be solve
by dividing it by the mass of the iron atom.
Number
of iron atoms = ( 0.5 kg) (1000g / 1kg) ( 1 iron atom / 9.27 x 10^-23 g)
<span>Number
of iron atoms = 5.39 x 10 ^24 iron atoms</span>
Answer:
T½ = 16hours
Explanation:
Final mass (N) = 10g
Initial mass (No) = 20g
Time (t) = 16hours
T½ = ?
T½ = In2 / λ
But λ = ?
In(N/No) = -λt
In(10/20) = -(λ * 16)
In(0.5) = -16λ
-0.693 = -16λ
λ = 0.693 / 16
λ = 0.0433
Note : λ is known as the disintegration constant
T½ = In2 / λ
T½ = 0.693 / 0.0433
T½ = 16hours
The half-life of the sample is 16hours
Answer:
Secondary consumers
Explanation:
Carnivores are organisms that only eat meat and that rely on others for food and energy; this means that they cannot produce food themselves.
Look at the answer choices:
- Decomposers: these are organisms that break down dead matter into material that can be used later by plants to grow; carnivores do not break down dead matter; rather, they eat meat.
- Primary consumers: these are usually herbivores; they are the second level of the energy pyramid, and they eat the organisms at the bottom level. The organisms at the bottom level are plants that make their own food. Obviously, plants are not meat, so carnivores are not primary consumers.
- Producers: these are the plants at the bottom of the energy pyramid that make their own food. Carnivores do not make their own food.
Thus, the answer is secondary consumers because this level of organisms eat the organisms at the primary consumer level.
Hope this helps!
Answer:
Shifts the equilibrium to the left. reduces solubility.
Explanation:
- MgF2(s) ↔ Mg2+(aq) + 2F-(aq)
S S 2S
∴ Ksp = 6.4 E-9 = [ Mg2+ ] * [ F- ]² = S * (2S)²
⇒ 4S² * S = 6.4 E-9
⇒ 4S³ = 6.4 E-9
⇒ S³ = 1.6 E-9
⇒ S = 1.1696 E-3 M
- NaF(s) → Na+(aq) + F-(aq)
0.10M 0.10M 0.10M
- MgF2(s) ↔ Mg2+(aq) + 2F-(aq)
S' S' 2S' + 0.10
⇒ Ksp = 6.4 E-9 = (S')*(2S' + 0.10)²
If we compare the concentration (0.10 M) of the ion with Ksp ( 6.4 E-9 ); thne we can neglect S' as adding:
⇒ 6.4 E-9 = (S')*(0.10)² = 0.01S'
⇒ S' = 6.4 E-7 M
∴ % S' = ( 6.4 E-7 / 0.1 )*100 = 6.4 E-4% <<< 5%, we can make the assumption
We can observe that S >> S' ( 1.1696 E-3 M >> 6.4 E-7 M ), which shows that the solubility is reduced by the efect of the common ion from the salt, which causes the equilibrium to shift to the left, precipitating part of MgF2(s).
