The average atomic mass of an element can be determined by multiplying the individual masses of the isotopes with their respective relative abundances, and adding them.
Average atomic mass of Br = 158 amu(0.2569) + 160 amu(0.4999) + 162 amu(0.2431)
Average atomic mass = 159.96 amu
As described in the problem, the relative abundance for Br-79 is 25.69%. This is because 2 atoms of Br is equal to 79*2 = 158 amu. Similarly, the relative abundance of Br-81 is 81*2 = 162, which is 24.31%.
Answer:
-125.4
Explanation:
Target equation is 4C(s) + 5H2(g) = C4H10
These are the data equations for enthalpy of combustion
- C(s) + O2(g) =O2(g) -393.5 kJ/mol * 4
- H2(g) + ½O2(g) =H20(l) = 285.8 kJ/mol * 5
- 2CO2(g) + 3H2O(l) = 13/2O2 (g) + C4H10 - 2877.1 reverse
To get target equation multiply data equation 1 by 4; multiply equation 2 by 5; and reverse equation 3, so...
Calculate 4(-393.5) + 5(-285.8) + 2877.6 and you should get the answer.
Answer:
The correct option is;
X, W, Y, Z
Explanation:
The parameters given are;
Spring (S), Spring Constant (N/m)
W, 24
X, 35
Y, 22
Z, 15
The equation for elastic potential energy,
, is 
The above equation can also be written as 
Where:
k = The spring constant in (N/m)
x = The spring extension
Therefore, since the elastic potential energy,
, of the spring is directly proportional to the spring constant, k, we have the springs with higher spring constant will have higher elastic potential energy,
, therefore the correct order is as follows;
X > W > Y > Z
The correct answer is that chemical changes form new compounds. Chemical change is a change where the substance changes in identity or form new substances after undergoing a process. On the other hand, a physical change is a change in the properties of matter that does not change the identity of the substance.
Answer:
Magnesium Difluoride
Explanation:
Mg = magnesium
F = fluoride
F2 = difluoride (prefix "di" indicates 2)