EVALUATIVE QUIZ MIDTERMS PART 1

Which type of bond and state of matter have the property of electric conductivity?

• ionic-solid

• ionic-aqueous

• covalent-aqueous

• metallic-solid

• covalent-solid

Answer explanation

All aqueous state of matter are able to conduct electricity as it contains water. However, covalent molecules generally cannot conduct electricity as they do not have free ions like metallic compounds have. Even pure water is unable to conduct electricity. The water in the environment contains metals and ionic salts that's why they are conductors. Solid ionic crystals are incapable of conducting electricity like sugar and salt crystals. They are able to conduct electricity when they are ionized in water (aqueous state) since they become free moving ions unlike in their crystal form. Electric conduction is possible as the electricity electrons will move or replace the electrons of the conductor continuously so electric flow is uninterrupted. Fun fact: You won't damage your phone if it fell in pure water. However, since environmental water has salt, it reacts with the metallic chips of phones, which may lead to erosion of metal. A way to repair this is to wash the motherboard with pure water to remove the salt. Putting in rice may be effective in removing moisture so the ions cannot move freely.

When electrons flow in electric current, it is attracted to the positively charged electrode called _____.

Answer explanation

Cathode is the negatively charged electrode that provides the negatively charged anions (have excess electrons). Anode is the positively charged electrode that attracts electricity (negatively charged) towards it. REMEMBER: OPPOSITE ATTRACTS.

When drawing a 3D molecule in Molview, which bond must be used to signify that the atom is away from you?

• sigma bond

• pi bond

• hash bond

• wedge bond

• Solid bond

Answer explanation

Hash or dashed bond (A) signifies that the bond is away from you while the wedge (B) bond means it is towards you. Solid line (C) means it is on the same plane ("flat"). Sigma means single bond while pi bond means double or triple bond.

What should I use if I need to draw an aromatic ring? Encircle your answer!

Answer explanation

The aromatic ring is also known as the Benzene ring. It is a 6-carbon ring with alternating pi bonds.

Practice drawing molecules in molview!

Which theory may be used to predict the shape of the molecule on the premise of that electron pairs repel each so bonds are angled at locations with least repulsion?

• Kossel-Lewis

• VSEPR Theory

• Valence bond theory

• Molecular orbital theory

Answer explanation

Kossel Lewis states that atoms bond to complete the octet rule, while VSEPR predicts shape based on electron repulsion. Valence bond states that covalent bonds are formed when two valence orbitals (half-filled) belonging to two different atoms overlap on each other. Lastly, molecular orbital theory states that each atom tends to combine together and form molecular orbitals. (the theories were discussed in the supplemental videos that were previously posted in the classroom)

If the compound in the provided picture is dissolved in water, which of the following IMF is FORMED?

• H-bond

• DP-DP

• Ion-DP

• vWFs

Answer explanation

As shown in the photo, there is no solid line between aluminum (metal) and OH (nonmetal) so the bond is ionic. Since it is dissolved in water, the ionic compound dissociates into its ionic forms: cation (Al 3+) and anion (OH1-). The ions overcome the H-bond between the water molecules so the cation forms an ion-DP forces with the partially negative Oxygen atom of water, while the anion forms ion-DP forces with the partially positive H atoms.

Balance the equation: __Cupric sulfate + __Aluminum nitrate --> _________ + __________

• 2,3,1,2

• 3,2,2,1

• 3,2,3,1

• 2,2,3,1

Answer explanation

How many moles of Nitrogen is needed to react with Oxygen to make 6 moles of Nitrogen monoxide?

• 1

• 2

• 3

• 4

Answer explanation

Since the mole ratio of nitrogen to nitrogen monoxide is 1:2, 6 moles of NO may be produced by 3 moles of Nitrogen and oxygen each.

What is the molecular formula of an oxide of boron that contains 40% boron? molar mass: 53.62g/mol

• BO

• B₂O₂

• B₂O₃

• BO₂

Answer explanation

To double check the answer, you can compute for the molar mass of the derived answer (B₂O₂). If the computed molar mass (10.81*2 + 16*2) is the same to the given molar mass (53.62g/mol), it is correct.

How many nitrate ions is present in 100g ferrous nitrate? (Fe=55.84g/mol; N=14g/mol; O=16g/mol)

• 4.98 x 10²³ ions

• 4.98 x 10²⁵ ions

• 6.7 x 10²³ ions

• 6.7 x 10²⁵ ions

Answer explanation

Always remember: cancel the units until you arrive at the desired unit.