Table Giving Answer
Element Atomic mass % Amount
Mg_24 24 79 18.96
Mg_25 25 10 2.5
Mg_26 26 11 2.86
Total 24.32
Discussion
The method of calculation for this table, which was done in Excel (a spread sheet) is shown below. Assume that there is 100 grams of material of "pure" magnesium. What is it's mass?
<em><u>Sample Calculation</u></em>
The the sample atomic mass = 24
Mass = % * sample atomic mass
Mass = 79% * 24
Mass = (79/100) * 24
Mass = 18.96
<em><u>Note</u></em>
The other two elements are found exactly the same as the sample calculation.
Then all you do is add the 3 masses together.
Answer
The mass of Mg to 1 decimal place is 24.3 <<<< Answer.
Answer:
7,94 minutes
Explanation:
If the descomposition of HBr(gr) into elemental species have a rate constant, then this reaction belongs to a zero-order reaction kinetics, where the r<em>eaction rate does not depend on the concentration of the reactants. </em>
For the zero-order reactions, concentration-time equation can be written as follows:
[A] = - Kt + [Ao]
where:
- [A]: concentration of the reactant A at the <em>t </em>time,
- [A]o: initial concentration of the reactant A,
- K: rate constant,
- t: elapsed time of the reaction
<u>To solve the problem, we just replace our data in the concentration-time equation, and we clear the value of t.</u>
Data:
K = 4.2 ×10−3atm/s,
[A]o=[HBr]o= 2 atm,
[A]=[HBr]=0 atm (all HBr(g) is gone)
<em>We clear the incognita :</em>
[A] = - Kt + [Ao]............. Kt = [Ao] - [A]
t = ([Ao] - [A])/K
<em>We replace the numerical values:</em>
t = (2 atm - 0 atm)/4.2 ×10−3atm/s = 476,19 s = 7,94 minutes
So, we need 7,94 minutes to achieve complete conversion into elements ([HBr]=0).
