Answer:
d = 43.5 g/cm³
Explanation:
Given data:
Mass of magnesium cube = 217.501 g
Volume of magnesium cube = 5.00 cm³
Density of magnesium cube = ?
Solution:
Formula:
d = m/v
d = density
m = mass
v = volume
by putting values,
d = 217.501 g/ 5.00 cm³
d = 43.5 g/cm³
Given:
Concentration of Fluoride ions = 0.100 M
Concentration of Hydrogen Fluoride = 0.126 M
Asked: Concentration of fluoride ions after the addition of 5ml of 0.0100 M HCl to 25 mL of the solution
Assume: 50:50 ratio of fluoride ions and HF
12.5ml*0.1mol/L *1L/1000mL + 12.5*0.126mol/L * 1L/1000mL = 2.825x10^-3 moles F-
5ml * 0.01 mol/L *1L/1000mL = 5x10^-5 moles
Assume: Volume additive
Final concentration = 2.825x10^-3 + 5x10^-5 moles/ 30 ml * 1000ml/L =0.0958 M
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27/208 = normality
12 x 10^-2 approx = normality
nw Ka = 14.3 x 10^-3
pKa = 3 - log 14
now, after getting the pKa put it in formula :
pH = pKa + log concn of ion/concn of salt and you'll get it
hope this helps
