The Relative Formula Mass of NaH2PO4 is 120 g/mol
Therefore, the number of moles = 6.6/120
= 0.055 moles of NaH2PO4 which is also equal to the number of moles of H2PO4.
[H2PO4-] = Number of moles oof H2PO4-/Volume of the solution in L
= 0.055/ ( 355 ×10^-3)
= 0.155 M
Na2HPO4 undergoes complete dissociation as follows;
Na2HPO4 (aq)= 2Na+ (aq) + HPO4^2- (aq)
1 mole of Na2HPO4 = 142 g/mol
Therefore; number of moles = 8.0/142
= 0.0563 moles
[HPO4 ^-2] is given by no of moles HPO4^2- /volume of the solution in L
= 0.0563/(355×10^-3)
= 0.1586 M
Both H2PO4^2- and HPO4^2- are weak acids the undergoes partial dissociation
Ka of H2PO4- = 6.20 × 10^-8
[H+] =Ka*([H2PO4-]/[HPO4(2-)]
= (6.20 ×10^-8)×(0.155/0.1586)
= 6.059 ×10^-8 M
pH = - log[H+]
= - log (6.059×10^-8)
= 7.218
Answer:
Explanation:
The volume and amount of gas are constant, so we can use Gay-Lussac’s Law:
At constant volume, the pressure exerted by a gas is directly proportional to its temperature.
Data:
p₁ =5.7 atm; T₁ = 100.0 °C
p₂ = ?; T₂ = 20.0 °C
Calculations:
1. Convert the temperatures to kelvins
T₁ = (100.0 + 273.15) K = 373.15
T₂ = (20.0 + 273.15) K = 293.15
2. Calculate the new pressure
Answer:
The new volume of the gas is 32L
Explanation:
P1 = 16atm
V1 = 4L
P2 = atm
V2 = ?
According to Boyle's law, the volume of a given mass of gas is inversely proportional to its volume provided the temperature remains constant.
P1 * V1 = P2 * V2
V2 = (P1 * V1) / P2
V2 = (16 * 4) / 2
V2 = 64 / 2
V2 = 32L
The new volume of the gas is 32L
Answer:
option C = 9.0 x 10²³ atoms
Explanation:
Data Given:
no. of moles of tin (Sn) atoms = 1.5 moles
no. of tin (Sn) atoms = ?
Solution:
Formula used to find number of atoms
no. of moles = no. of atoms / Avogadro's number
Rearrange the above equation:
no. of atoms = no. of moles x Avogadro's number . . . . . . (1)
Where
Avogadro's number = 6.022 x 10²³
Put values in equation 1
no. of atoms = 1.5 x 6.022 x 10²³
no. of atoms = 9.033 x 10²³
Round the figure = 9.0 x 10²³ atoms
So option C is correct
