Answer:C is most likely a metalloid
Explanation:A is a metal while B is a non metal. This is because when we look at the properties of metals, they are very lustrous and have a high conductivity. On the other hand, non metals are the opposite but metalloids have properties the are inbetween ie, they react with either an acid or base, and have a medium electrical conductivity unlike metals(high) anc non metals(low).
Total change in energy = Heat produced by system + work done on the system
= 228 - 55
= 173 kJ
Because this energy is released as heat, the reaction is exothermic.
Answer:
Unbalanced
Explanation:
The reaction equation is given as:
H₂ + O₂ → 2H₂O
The given reaction flouts the law of conservation of mass and it is not balanced. To know a reaction that is balanced, the number of atoms on both sides of the expression must be the same;
Number of moles
Reactants Products
Hydrogen 2 4
Oxygen 2 2
We see that the hydrogen atoms are not balanced.
Answer:
4.96E-8 moles of Cu(OH)2
Explanation:
Kps es the constant referring to how much a substance can be dissolved in water. Using Kps, it is possible to know the concentration of weak electrolytes. Then, pKps is the minus logarithm of Kps.
Now, we know that sodium hydroxide (NaOH) is a strong electrolyte, who is completely dissolved in water. Therefore the pH depends only on OH concentration originating from NaOH. Let us to figure out how much is that OH concentration.
![pH= -log[H]\\pH= -log (\frac{kw}{[OH]})](https://tex.z-dn.net/?f=pH%3D%20-log%5BH%5D%5C%5CpH%3D%20-log%20%28%5Cfrac%7Bkw%7D%7B%5BOH%5D%7D%29)
![8.23 = - log(\frac{Kw}{[OH]} \\10^{-8.23} = Kw/[OH]\\ [OH] = Kw/10^{-8.23}](https://tex.z-dn.net/?f=8.23%20%3D%20-%20log%28%5Cfrac%7BKw%7D%7B%5BOH%5D%7D%20%5C%5C10%5E%7B-8.23%7D%20%3D%20Kw%2F%5BOH%5D%5C%5C%20%5BOH%5D%20%3D%20Kw%2F10%5E%7B-8.23%7D)
![[OH]=1.69E-6](https://tex.z-dn.net/?f=%5BOH%5D%3D1.69E-6)
This concentration of OH affects the disociation of Cu(OH)2. Let us see the dissociation reaction:
In the equilibrum, exist a concentration of OH already, that we knew, and it will be added that from dissociation, called "s":
The expression for Kps is:
![Kps= [Cu^{2+}] [OH]^2](https://tex.z-dn.net/?f=Kps%3D%20%5BCu%5E%7B2%2B%7D%5D%20%5BOH%5D%5E2)
The moles of (CuOH)2 soluble are limitated for the concentration of OH present, according to the next equation.
"s" is the soluble quantity of Cu(OH)2.
The solution for this third grade equation is 
Now, let us calculate the moles in 1 L:
We can use the reactivity series of metals to solve this.
The reactivity series of metals are (in descending order) :
Potassium, sodium, Lithium, calcium, Magnesium, aluminum, zinc, iron, tin, lead, copper, mercury, silver, platinum, gold.
Since Potassium is the most reactive, the reaction with water should produce extremely violent gas.
Sodium is the next most reactive, so it should produce violent gas.
And Lithium is the least reactive out of the 3 metals, so it should be strong gas formation.
In addition, the gas produced should be hydrogen, since the reaction of metals should water should produce "metal name" hydroxide + hydrogen.
