Answer:
0.218 M of Pb(NO3)2
Explanation:
Equation of the reaction
Pb(NO3)2(aq) + 2NaCl(aq) --> PbCl2(s) + 2NaNO3(aq)
1 mole of Pb(NO3)2 reacts to precipitate 1 mole of PbCl2
Molar mass of PbCl2 = 207 + (35.5*2)
= 278 g/mol
Number of moles of PbCl2 precipitated = mass/molar mass
= 12.11/278
= 0.04356 mol
Since 0.04356 moles of PbCl2 was precipitated, therefore by stoichiometry; 0.04356 moles of Pb(NO3)2 reacted.
Molarity is defined as the number of moles of solute in 1 liter of solution.
Molarity = number of moles/volumes
= 0.04356/0.2
= 0.218 M
answer:
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Answer:
2 elements and one compund i think
Explanation:
The half-life of cobalt-60 is 5.26 years. After 10.52 years, 5 grams of a 20-gram sample will remain is TRUE
<u>Explanation:</u>
Mass of cobalt = 20 g
Half-life = 5.26 years
Mass remains after 10.52 years = 5 g
This can be solved by using given below formula, 
= initial mass
t = number of years from when the mass was m_0
m(t) = remaining mass after t years
Number of half-lives = 
Number of half-lives = 
Number of half-lives = 2
At time zero = 20 g
At first half-life =
= 10 g
At second half life =
= 5 g
The given statement is true.