The answer is 2 electrons.
The electron configuration of calcium is 2:8:8:2
Calcium has two electrons in its outermost shell. These are its valence electrons and are the ones used in bonding with other elements. Valence electrons of an atom are those electrons that are in its outer energy shell or that are available for bonding.
Calcium is a metal. When metals react with non-metals, electrons are transferred from the metal atoms to the non-metal atoms forming ions. The resulting compound is known as an ionic compound.
For example, when calcium metal reacts with chlorine gas, calcium gives up its two valence electrons and Chlorine accepts them resulting in a new substance called calcium chloride in which the two elements have ended up forming ionic bonds.
Answer:
A. has an internal structure consisting of a membrane–bound nucleus and membrane–bound organelles
Explanation:
Answer:
a) 24.31 g
b) 16.69 g
Explanation:
A mixture of CO2 and Kr weighs 41.0 g and exerts a pressure of 0.729 atm in its container.
After the CO2 is completely removed by absorption with NaOH(s), the pressure in the container is 0.193 atm.
Therefore, Pressure of Kr = 0.193 atm
Pressure of CO2 = 0.729 - 0.193 = 0.536 atm
Their mole fraction can be also determined as follows:
CO2 = 
CO2 = 
= 0.735
Also; for Kr ; we have
Kr = 
Kr = 0.265
Molar mass of CO2 = 44 g/mol
Molar mass of Kr = 83.78 g/mol
Mass of CO2 = mole fraction * molar mass = 0.735 * 44 = 32.34
Mass of Kr = 0.265 * 83.78 = 22.20
Total mass = 32.34 +22.20 = 54.54
The Percentage of gas in mixture is as follows:
% CO2 = 
* 100 %
= 0.5930
= 59.30%
(a) Mass of CO2 in mixture = 0.5930* 41 g = 24.31 g
% Kr =
* 100 %
= 0.407
= 40.70 %
(b) Mass of Kr in mixture = 0.407 * 41 = 16.69 g
Answer:
The 99.68% of the aspirin is present in the neutral form
Explanation:
Aspirin, Acetylsalicylic acid, is a weak acid with pKa = 3.5
Using Henderson-Hasselbalch equation:
pH = pKa + log [A⁻] / [HA]
<em>Where [A⁻] is the ionized form and HA the neutral form of the acid</em>
<em />
Replacing with a pH of stomach of 1.0:
1.0 = 3.5 + log [A⁻] / [HA]
-2.5 = log [A⁻] / [HA]
3.16x10⁻³ = [A⁻] / [HA] <em>(1)</em>
<em />
A 100% of aspirin is = [A⁻] + [HA]
100 = [A⁻] + [HA] <em>(2)</em>
<em></em>
Replacing (2) in (1)
3.16x10⁻³ = 100 - [HA] / [HA]
3.16x10⁻³[HA] = 100 - [HA]
1.00316 [HA] = 100
[HA] = 99.68%
<h3>The 99.68% of the aspirin is present in the neutral form</h3>
Answer:
[S₂] = 1.27×10⁻⁷ M
Explanation:
2 H₂S(g) ⇄ 2 H₂(g) + S₂(g), Kc=1,625x10⁻⁷
The equation of this reaction is:
1,625x10⁻⁷ = ![\frac{[H_2]^2[S_2]}{[H_{2}S]^2}](https://tex.z-dn.net/?f=%5Cfrac%7B%5BH_2%5D%5E2%5BS_2%5D%7D%7B%5BH_%7B2%7DS%5D%5E2%7D)
The equilibrium concentrations are:
[H₂S] = 0,162 - 2x
[H₂] = 0,184 + 2x
[S₂] = x
Replacing:
1,625x10⁻⁷ = ![\frac{[0,184+2x]^2[x]}{[0,162-2x]^2}](https://tex.z-dn.net/?f=%5Cfrac%7B%5B0%2C184%2B2x%5D%5E2%5Bx%5D%7D%7B%5B0%2C162-2x%5D%5E2%7D)
Solving:
4x³ + 0,736x² + 0,033856x - 4,3x10⁻⁹
x = 1.27×10⁻⁷
Thus, concentration of S₂ is:
<em>[S₂] = 1.27×10⁻⁷ M</em>
