Question

1. Give the electron configuration for the chloride ion.

2. What is the percent by mass of hydrogen is aspirin, C9H8O4?

Answer 1

1. [Ne] 3s2 3p5
2. 4.48%

Answer 2

(1) The electron configuration for the chloride ion will be,

`1s^22s^22p^63s^23p^6`

(2) The percent by mass of hydrogen in aspirin,
`C_9H_8O_4` is, 4.44%

Explanation for Part 1 :

Element = chlorine

Atomic number = 17

As we know that the number of electrons is equal to the atomic number.

So, the number of electrons = 17

An electronic configuration of neutral chlorine element is,

`1s^22s^22p^63s^23p^5`

The chloride ion formed by the addition of an electron in chlorine element.

So, the electron configuration for the chloride ion will be,

`1s^22s^22p^63s^23p^6`

Explanation for Part 2 :

Mass of carbon = 12 g/mole

Mass of hydrogen = 1 g/mole

Mass of oxygen = 16 g/mole

The given compound is aspirin,
`C_9H_8O_4`

The molar mass of aspirin,
`C_9H_8O_4` = 9(12) + 8(1) + 4(16) = 180 g/mole

In the given compound, there are 9 atoms of carbon, 8 atoms of hydrogen and 4 atoms of oxygen.

The mass of hydrogen in aspirin = 8 g/mole

Now we have to calculate the percent mass of hydrogen in aspirin.

`\%\text{ by mass of hydrogen}=\frac{\text{Mass of hydrogen}}{\text{Mass of aspirin}}* 100=(8)/(180)* 100=4.44\%`

Therefore, the percent by mass of hydrogen in aspirin,
`C_9H_8O_4` is, 4.44%