Pre lab questions chemistry answers

Chemical Bonding

pre-lab Questions
Draw an electron dot diagram for methane.

Use Figure 9 and the periodic table (Figure 2) to construct a hypothesis about the melting points of stearic acid and sodium chloride. How will they compare, and how does that relate to the bonds that hold atoms in the compounds together?

Y:\ESL Kits\2nd Edition General Chemistry\2_Multimedia\Images\Lab 7 Chemical Bonding\Figure 5.png

Figure 9: Structure of Stearic Acid

experiment 1: Structural Models
Data Sheet
Table 1: Structural Models Data

Atom

Number of Valence Electrons

Hydrogen

Chlorine

Sodium

Oxygen

Magnesium

Potassium

Bromine

Fluorine

Table 2: Compound Models Data

Compound

Type of Bond

HCl

NaCl

KBr

MgO

H2

O2

HF

Post-Lab Questions
1. Describe the differences between covalent and ionic bonds.

Use the periodic table to describe which elements form ionic bonds, and which elements form covalent bonds.

experiment 2: melting points and types of bonds
Data Sheet
Table 3: Melting Point Data

Compound Name

Time the Compound Took to Melt (sec)

Melting Order (or, indicate if the compound did not melt)

Type of Bond

Sucrose

Sodium Chloride

Stearic Acid

Post-Lab Questions
1. Which compound melted first? Did this agree with your prediction from Pre-Lab Question 2? Explain why or why not.

1. Did any bubbling compounds release an odor or undergo a color change?

1. Which of the three samples in these experiments have covalent bonds? Which samples have ionic bonds? Explain your answer using data from the experiment.

1. What did stearic acid look like before and after it was exposed to heat? Use the law of conservation of matter to explain your answer.

1. Use the concept of melting point to explain why some plastics can’t be used to microwave food.