Answer:
Taking into account the definition of average atomic mass and isotopes of an element, the information that you need is the masses of its isotopes and their percent abundances.
Each chemical element is characterized by the number of protons in its nucleus, which is called the atomic number Z.
But in the nucleus of each element it is also possible to find neutrons, whose number can vary. The atomic mass (A) is obtained by adding the number of protons and neutrons in a given nucleus.
The same chemical element can be made up of different atoms, that is, their atomic numbers are the same, but the number of neutrons is different. These atoms are called isotopes of the element.
The atomic mass of an element is the weighted average mass of its natural isotopes. Therefore, the atomic mass of an element is not a whole number.
The weighted average means that not all isotopes have the same percentage.
In other words, the atomic masses of chemical elements are usually calculated as the weighted average of the masses of the different isotopes of each element, taking into account the relative abundance of each of them.
Explanation:
ones that are answered through observing :)
Answer:
Percent by mass of water is 56%
Explanation:
First of all calculate the mass of hydrated compound as,
Mass of Sodium = Na × 2 = 22.99 × 1 = 45.98 g
Mass of Sulfur = S × 1 = 32.06 × 1 = 32.06 g
Mass of Oxygen = O × 14 = 16 × 14 = 224 g
Mass of Hydrogen = H × 20 = 1.01 × 20 = 20.2 g
Mass of Na₂S0₄.10H₂O = 322.24 g
Secondly, calculate mass of water present in hydrated compound. For this one should look for the coefficient present before H₂O in molecular formula of hydrated compound. In this case the coefficient is 10, so the mass of water is...
Mass of water = 10 × 18.02
Mass of water = 180.2 g
Now, we will apply following formula to find percent of water in hydrated compound,
%H₂O = Mass of H₂O / Mass of Hydrated Compound × 100
Putting values,
%H₂O = 180.2 g / 322.24 g × 100
%H₂O = 55.92 % ≈ 56%
Answer:
HCI(aq)+CH3COONa(s) ----> CH3COOH(aq)+NaCl(s)
NaOH(aq)+CH3COOH(aq) ----> CH3COONa(s)+H2O(l)
Explanation:
A buffer is a solution that resists changes in acidity or alkalinity. A buffer is able to neutralize a little amount of acid or base thereby maintaining the pH of the system at a steady value.
A buffer may be an aqueous solution of a weak acid and its conjugate base or a weak base and its conjugate acid.
The equations for the neutralizations that occurred upon addition of HCl or NaOH are;
HCI(aq)+CH3COONa(s) ----> CH3COOH(aq)+NaCl(s)
NaOH(aq)+CH3COOH(aq) ----> CH3COONa(s)+H2O(l)
