The value of X is 10 hence the formula of unknown hydrate sodium sulfate is NaSO4.10 H20
calculation
step 1:find the moles of NaSO4 and the moles of H2O
moles= mass/molar mass
moles of Na2SO4=1.42÷142=0.01 moles
moles of H20= mass of H2O/molar mass of H2O
mass of H2O= 3.22-1.42=1.8g
mole of H2O is therefore 1.8÷18=0.1 moles
step 2: find the mole ratio by dividing each mole by smallest number of mole (0.01)
that is Na2So4= 0.01/0.01 =1
H2O= 0.1/0.01=10
718.65 degrees is the initial temperature of the zinc metal sample.
Explanation:
Data given:
mass of zinc sample = 2.50 grams
mass of water = 65 grams
initial temperature of water = 20 degrees
final temperature of water = 22.5 degrees
ΔT = change in temperature of water is 2.50 degrees
specific heat capacity of zinc cp= 0.390 J/g°C
initial temperature of zinc sample = ?
cp of water = 4.186 J/g°C
heat absorbed = heat released (no heat loss)
formula used is
q = mcΔT
q water = 65 x 4.286 x 2.5
q water = 696.15 J
q zinc = 2.50 x 0.390 x (22.50- Ti)
equating the two equations
696.15 = - 22.50+ Ti
Ti = 718.65 degrees is the initial temperature of zinc.
Answer: The stick model method
Answer:
9.88
Explanation:
As higher is the Ksp, more soluble is the compound. So, Co(OH)₂ is the less soluble hydroxide.
The maximum concentration of it must be 1x10⁻⁶ M, and the reaction is:
Co(OH)₂(s) ⇄ Co⁺²(aq) + 2OH⁻(aq)
So, [Co⁺²] = 1x10⁻⁶M
Ksp = [Co⁺²] *[OH⁻]²
[OH⁻]² = 5.9x10⁻¹⁵/1x10⁻⁶
[OH⁻] = √(5.9x10⁻⁹)
[OH⁻] = 7.6811x10⁻⁵
pOH = -log[OH⁻]
pOH = -log(7.6811x10⁻⁵)
pOH = 4.11
Knowing that pH + pOH = 14
pH = 14 - 4.11
pH = 9.88
Answer:
1.85 × 10⁻⁶
Explanation:
0.0003 ÷ 162 = 1.851851852 × 10⁻⁶ ⇒ 1.85 × 10⁻⁶
Hope that helps.
