Answer:
Explanation:
a )
m = m₀
m is mass after time t . original mass is m₀ , λ is disintegration constant
λ = .693 / half life
= .693 / 1590
= .0004358
m = m₀
b )
m = 50 x
= 40.21 mg .
c )
40 = 50
.8 =
= 1.25
.0004358 t = .22314
t = 512 years .
Answer:
0.97 kg, 1.0kg
Explanation:
As you have mentioned in the question, to convert kilo-gram to grams, this conversion is used, 1 kilogram = 1,000 grams
Initially, when one has to convert from one unit to another, there is a lot of confusion. To avoid any such, multiply and divide the number with units to which it has to be converted.
Here,
970 g =
This makes no difference to the number.
970 g =
As, 1 kg= 1,000 g
970 g =
970 g = 0.97 kg
Rounding this off to the nearest tenth of a kilogram.
The tenths place is immediately to the right of the decimal point.
Here, 9 is at the tenth's place. Round the tenth's place up if the digit at hundredth's place is greater than or equal to 5. Since, 7 > 5, up the number at tenth's place.
So, answer is 1.0 kg
Answer:
The mass percent of Al(OH)₃ is 15.3%
Explanation:
The reaction is:
Al(OH)₃ + 3HCl = AlCl₃ + 3H₂O
The excess acid is neutralized with a solution of sodium hidroxide, in the reaction:
NaOH + HCl = NaCl + H₂O
The total moles of HCl is:
From the second titration, the moles of excess of HCl is:
The difference between the total and excess of HCl, it can be know the moles that reacts with the aluminum hydroxide, is:
The ratio between HCl and Al(OH)₃ is 3:1. The MW for aluminum hydroxide is 78 g/mol, thus:
The percentage of Al(OH)₃ is:
%