Unit 4.04 - 4.06

Question 1

When can a change be seen as physical?

Answer 1

If there is only an interruption in the inter-molecular forces

Question 2

When can a change be seen as chemical?

Answer 2

If there is a re-arrangement of the intra (covalent or ionic) bonds

Question 3

Explain the difference between IMF and intra bonds

Answer 3

IMF deals with the forces of attraction/repulsion in the molecule. For example, London Dispersion and Hydrogen bonding. Intra bonds deal with the bonds themselves such as the covalent or ionic bond.

Question 4

What are chemical reactions often carried out between?

Answer 4

substances that are in a solution (dissolved in a solvent, usually water)

Question 5

Define titration

Answer 5

Is the name given to the experimental method of analysis that utilizes concentrations of solutions.

Question 6

Unlike gravimetric analysis, what doesn’t form and what can we do to solve this problem?

Answer 6

Solid doesn’t form, so we have to have another way of determining that the analyte has been totally consumed. This is done by using an indicator that changes color at the equivalence point (the point at which the stoichiometric molar ratio has been achieved). The observable event of a color change that occurs at the equivalence point is called the end point.

Question 7

Explain the steps of proper use of a buret

Answer 7

1. A buret should be rinsed two times with the titrant before use
2. Fill the buret with the titrant above the zero
3. Drain the titrant to the zero or below
4. Never drain a buret below the highest graduation.