Answer:
pH= 3.30
Explanation:
Hydrochloric acid is a strong acid that completely dissociates in water.
For a 0.00050 M HCl solution the concentration of the hydrogen ions, [
H
+
]
, is 0.00050 moles/liter (i.e. 0.025 M).
The pH is defined as −
log
[
H
+
]
.
Substituting 0.00050 into the equation for pH we find that the 0.00050 M HCl solution has a pH of -log(0.00050) = 3.30.
Enthalpy change is the term given to the concentration of the heat absorbed or evolved in a reaction carried out at a constant pressure. It is given by the symbol ΔH.
Enthalpy change = m (Cwater × dT + Hvap + Csteam × dT
dHvap = 40.67 kJ/mol = 40.67 × 103/18 = 2259.4 J/g
Enthalpy change = 5.00 [4.18 × (100-14) + 2259.4 + 1.84 × (115-100)]
= 13232.4 J
Answer:
..........................
Explanation:
........................
From the periodic table:
molecular mass of carbon = 12 grams
molecular mass of fluorine = 18.99 grams
molecular mass of chlorine = 35.5 grams
Therefore:
one mole of CF2Cl2 = 12 + 2(18.99) + 2(35.5) = 120.98 grams
Therefore, we can use cross multiplication to find the number of moles in 79.34 grams as follows:
mass = (79.34 x 1) / 120.98 = 0.6558 moles
Now, one mole contains 6.022 x 10^23 molecules, therefore:
number of molecules in 0.65548 moles = 0.6558 x 6.022 x 10^23
= 3.949 x 10^23 molecules
