atomic mass=percentage of isotope a * mass of isotope a + percentage of isotope b * mass of isotope b+...+percentage of isotope n * mass of isotope n.
Data:
mass of isotope₁=267.8 u
percentage of isotope₁=90.3%
mass of isotope₂=270.9 u
percentage of isotope₂=9.7%
Therefore:
atomic mass=(0.903)(267.8 u)+(0.097)(270.9 u)=
=241.8234 u + 26.2773 u≈268.1 u
Answer: the mass atomic of this element would be 268.1 u
Answer:
Reactants break bonds with consuming the energy and form the new bonds .
Explanation:
As the two molecules interacted with each other , the elements reshuffled the bonds and formed the new ones with shifting the energy and converting it into new products .
Answer:
0.136g
Explanation:
A student dissolved 5.00 g of Co(NO3)2 in enough water to make 100. mL of stock solution. He took 4.00 mL of the stock solution and then diluted it with water to give 275. mL of a final solution. How many grams of NO3- ion are there in the final solution?
Initial mole of Co(NO3)2 
Mole of Co(NO3)2 in final solution
Mole of NO3- in final solution = 2 x Mole of Co(NO3)2
Mass of NO3- in final solution is mole x Molar mass of NO3
