Answer:
16.89g of PbBr2
Explanation:
First, let us calculate the number of mole of Pb(NO3)2. This is illustrated below:
Molarity of Pb(NO3)2 = 0.595M
Volume = 77mL = 77/1000 = 0.077L
Mole =?
Molarity = mole/Volume
Mole = Molarity x Volume
Mole of Pb(NO3)2 = 0.595x0.077
Mole of Pb(NO3)2 = 0.046mol
Convert 0.046mol of Pb(NO3)2 to grams as shown below:
Molar Mass of Pb(NO3)2 =
207 + 2[ 14 + (16x3)]
= 207 + 2[14 + 48]
= 207 + 2[62] = 207 +124 = 331g/mol
Mass of Pb(NO3)2 = number of mole x molar Mass = 0.046 x 331 = 15.23g
Molar Mass of PbBr2 = 207 + (2x80) = 207 + 160 = 367g/mol
Equation for the reaction is given below:
Pb(NO3)2 + CuBr2 —> PbBr2 + Cu(NO3)2
From the equation above,
331g of Pb(NO3)2 precipitated 367g of PbBr2
Therefore, 15.23g of Pb(NO3)2 will precipitate = (15.23x367)/331 = 16.89g of PbBr2
The water would become polluted.
Answer:
6.113 atm
Explanation:
Data provided in the question:
Molarity of the solution = 0.25 M
Temperature, T = 25° C = 25 + 273 = 298 K
Now,
Osmotic pressure (π) is given as:
π = MRT
where,
M is the molarity of the solution
R is the ideal gas constant = 0.082057 L atm mol⁻¹K⁻¹
on substituting the respective values, we get
π = 0.25 × 0.082057 × 298
or
π = 6.113 atm
I would say that descriptive investigations aren't repeatable because it means that you are only describing something - you ask certain question about something, but do not form a hypothesis at that point yet. So it would be a waste of time to simply ask the same questions over and over again with no hypothesis to prove, which is why these types of investigations cannot be repeated.
