The answer is (3) Cu2O. Copper (I) has an oxidation state of +1 (that's what the "I" indicates). You can also think of this as copper (I) having a charge of +1. Oxygen has an oxidation state of -2 (that's just a rule you have to know), and you can think of it as oxygen having a charge of -2. You need oxidation numbers in a neutral compound to add up to 0 (or charges in a neutral compond to add up to 0), so you need two Cu to balance the O, which is Cu2O.
Answer:
900 J/mol
Explanation:
Data provided:
Enthalpy of the pure liquid at 75° C = 100 J/mol
Enthalpy of the pure vapor at 75° C = 1000 J/mol
Now,
the heat of vaporization is the the change in enthalpy from the liquid state to the vapor stage.
Thus, mathematically,
The heat of vaporization at 75° C
= Enthalpy of the pure vapor at 75° C - Enthalpy of the pure liquid at 75° C
on substituting the values, we get
The heat of vaporization at 75° C = 1000 J/mol - 100 J/mol
or
The heat of vaporization at 75° C = 900 J/mol
Answer:
pH = 11.3
Explanation:
From the question given above, the following data were obtained:
Concentration of hydronium ion [H₃O⁺] = 4.950×10¯¹² M
pH =.?
The pH of a solution is defined by the following equation:
pH = –Log [H₃O⁺]
Thus, with the above formula, we can obtain the pH of the solution as follow:
Concentration of hydronium ion [H₃O⁺] = 4.950×10¯¹² M
pH =.?
pH = –Log [H₃O⁺]
pH = –Log 4.950×10¯¹²
pH = 11.3
65 grams of HCl = 65/36.5 moles of HCl = 1.78 moles
1.78 moles of HCl dissolved to make a 5 litres of solution has a concentration of 1.78/5 = 0.36 mol/dm^3 (Note: 1 litre = 1 cubic decimetre)
In a strong acid, such as HCl, [H+] = [acid], so [H+] = 0.36
To calculate pH, we have to take the negative logarithm of the concentration of protons
So, -log(0.36) = 0.45
Hope I helped!! xx
