State one qualitative and one quantitative statement of the following : water, sodium hydroxide, air, gold, mercury, carbon,iron
1 answer:
You might be interested in
First, isotopes <u>are the atoms of a single element whose nuclei have a different number of neutrons</u>, and therefore, differ in mass numbers. You should know that atoms are formed by a nucleus that has a small size and is made up of protons and neutrons. The nucleus is surrounded by a cloud of electrons, which are found in a region of the atom called the cortex.
The mass number, represented as A, <u>is the sum of the number of protons and neutrons in the nucleus</u>. On the other hand, the atomic number (Z) is <u>the number of protons that exist in the nucleus. </u>
The isotopes of an element X are represented as follows,
<em>(see first attached picture)</em>
It should be noted that the number of neutrons of a chemical element can be calculated as the difference A-Z.
<u>The atomic and mass numbers of bismuth with 125 neutrons are</u>:
Z = 83
A = 83 + 125 = 208
Thus, the atomic symbol of the bismuth isotope with 125 neutrons is:
<em>(see second attached picture)</em>
Answer: 35.4 grams
Explanation:
Molarity of a solution is defined as the number of moles of solute dissolved per Liter of the solution.
where,
Molality = 2.65
n= moles of solute =?
= volume of solution in ml = 445 ml
Putting in the values we get:
Mass of solute in g=
Thus 35.4 grams of is needed to prepare 445 ml of a 2.65 m solution of
.