Acid and Base
What will happen if you mix a strong acid like hydrochloric acid with a strong base like sodium hydroxide?
They will undergo a neutralization reaction, forming water and a salt (in this case, sodium chloride).
Why does adding lemon juice (acidic) to fish reduce its “fishy” smell?
The basic amines in fish react with citric acid in lemon → form ammonium salts, which are not volatile → smell is reduced.
I look like a sphere around the nucleus, and I’m the very first place electrons like to be.
Who am I?
The 1s orbital
When I dissolve in water, I disappear, but I’m still there. Sugar and salt love being me in your tea or soup.
Who am I?
Solute
How can red cabbage be used to test for acids and bases?
Red cabbage contains a natural pH indicator called anthocyanin. When boiled in water, it creates a purple solution that changes color depending on the pH:
Acidic solutions turn it red/pink
Neutral solutions keep it purple
Basic solutions turn it green/yellow
You breathe me in every second, and I help you stay alive. I’m the most abundant gas in the air and sit in Group 15 of the periodic table.
Who am I?
Nitrogen (N)
Why does methane (CH₄) always form a tetrahedral shape, even though the carbon atom is “just one” element?
Carbon undergoes sp³ hybridization → four identical orbitals arrange tetrahedrally to minimize electron repulsion.
You add 5 grams of salt (NaCl) to a 250 mL pot of soup.
What is the mass/volume percent concentration of salt in the soup?
Mass of solute = 5 g
Volume of solution = 250 mL
%(m/v) = (5/250)* 100 = 2%
Why does pure water have a pH of 7, but rainwater is slightly acidic?
Pure water is neutral, with a pH of 7, because it has equal concentrations of hydrogen and hydroxide ions. Rainwater, however, dissolves carbon dioxide (CO₂) from the air, forming a weak acid called carbonic acid (H₂CO₃). This makes rainwater slightly acidic, usually around pH 5.5.
I result from a complete electron transfer. One atom gives, the other takes. I hold salts together and make solutions conduct electricity.
Ionic bond
Why does copper chloride (CuCl₂) produce a green-blue color, while strontium chloride (SrCl₂) produces a red color in fireworks?
Different metal ions have different electron energy levels. The energy released when electrons return to ground state corresponds to different wavelengths of visible light.
A nurse needs to prepare 500 mL of a 0.9 M NaCl solution.
How many grams of NaCl are needed? (Molar mass of NaCl = 58.5 g/mol)
Moles = Molarity × Volume = 0.9 × 0.5 = 0.45 mol
Mass = 0.45 × 58.5 = 26.33 grams
What is the pH of a 0.001 M HCl solution?
[H+]=0.001 M=1×10−3 pH=−log(1×10−3)=3\text{pH} = -\log(1 \times 10^{-3}) = 3pH=−log(1×10−3)=3
If you add more water to me, I decrease. If you evaporate water, I increase. I stay the same only when volume and solute stay unchanged.
Who am I?
Molarity
A neutral atom has an electron configuration of 1s22s22p63s23p4.
What element is this?
How many unpaired electrons does this atom have in its ground state, and in which orbital(s) are they located?
The electron configuration 1s22s22p63s23p4 has 2+2+6+2+4=16 electrons. A neutral atom with 16 electrons is Sulfur (S).
The valence configuration is 3s23p4. According to Hund's rule, the four electrons in the 3p sublevel are distributed as follows: three electrons are placed in separate 3p orbitals before the fourth electron is paired. This leaves two unpaired electrons in the 3p orbitals.
I tell you how much solute dissolves in a solvent at a specific temperature, but I’m not constant — heat me up, and I usually rise.
I’m often found in tables and used by chemists to prepare solutions perfectly.
Solubility