Answer:
4.8 %
Explanation:
We are asked the concentration in % by mass, given the molarity of the solution and its density.
0.8 molar solution means that we have 0.80 moles of acetic acid in 1 liter of solution. If we convert the moles of acetic acid to grams, and the 1 liter solution to grams, since we are given the density of solution, we will have the values necessary to calculate the % by mass:
MW acetic acid = 60.0 g/mol
mass acetic acid (the solute) = 0.80 mol x 60 g / mol = 48.00 g
mass of solution = 1000 cm³ x 1.010 g/ cm³ (1l= 1000 cm³)
= 1010 g
% (by mass) = 48.00 g/ 1010 g x 100 = 4.8 %
The mass number of an atom is its total number of protons and neutrons. Atoms of different elements usually have different mass numbers , but they can be the same. For example, the mass number of argon atoms and calcium atoms can both be 40.
Sorry but NaCl is a ionic compound not an element though it's made up of two elements sodium and chlorine
Explanation:
The reaction equation will be as follows.
Using bond energies, expression for calculating the value of 
is as follows.
On reactant side, from 
number of bonds are as follows.
C-C bonds = 1
C-H bonds = 6
From 
; Cl-Cl bonds = 1
On product side, from 
number of bonds are as follows.
C-C bonds = 1
C-H bonds = 5
C-Cl bonds = 1
From HCl; H-Cl bonds = 1
Hence, using the bond energies we will calculate the enthalpy of reaction as follows.
=![[(1 \times 348 kJ/mol) + (6 \times 414 kJ/mol) + (1 \times 242 kJ/mol)] - [(1 \times 348 kJ/mol) + (5 \times 414 kJ/mol) + (1 \times 327 kJ/mol) + (1 \times 431 kJ/mol)]](https://tex.z-dn.net/?f=%5B%281%20%5Ctimes%20348%20kJ%2Fmol%29%20%2B%20%286%20%5Ctimes%20414%20kJ%2Fmol%29%20%2B%20%281%20%5Ctimes%20242%20kJ%2Fmol%29%5D%20-%20%5B%281%20%5Ctimes%20348%20kJ%2Fmol%29%20%2B%20%285%20%5Ctimes%20414%20kJ%2Fmol%29%20%2B%20%281%20%5Ctimes%20327%20kJ%2Fmol%29%20%2B%20%281%20%5Ctimes%20431%20kJ%2Fmol%29%5D)
= -102 kJ/mol
Thus, we can conclude that change in enthalpy for the given reaction is -102 kJ/mol.
