Atoms & Ions
What is the charge of a proton?
Positive (+)
Write the chemical formula for magnesium chloride.
MgCl2
Balance: H₂ + O₂ → H₂O
2H₂ + O₂ → 2H₂O
What does molarity measure?
Moles of solute per liter of solution.
What color does blue litmus paper turn in an acidic solution?
A soil sample has a pH of 5.5. Is it acidic, neutral, or basic?
Acidic
An atom has 11 protons and 10 electrons. What ion is formed?
Na⁺ (+1 cation)
Name FeCl₃
Iron(III) chloride
Classify:
2KClO₃ → 2KCl + 3O₂
Decomposition reaction
What is the molarity of 1.0 mol NaCl in 2.0 L of solution?
0.5 M
What are the products of an acid–base neutralization reaction?
Salt and water
Farmers dissolve a fertilizer in water before application. In this solution, what is the solvent?
Water
What is the difference between isotopes of the same element?
They have the same number of protons but different numbers of neutrons.
Write the formula for aluminum sulfate
Al2(SO4)3
How many moles are in 36 g of H₂O?
2 moles
How many moles of solute are present in 250 mL of a 2.0 M solution?
0.50 mol
Classify a solution with pH 3.
Acidic solution
A fertilizer solution contains 0.30 mol KNO₃ in 1.5 L of solution. What is its molarity?
0.20 M
An ion has 17 protons and 18 electrons. Identify the ion and its charge.
Cl⁻, chloride ion, charge −1.
A compound contains Ca²⁺ and PO₄³⁻. Write the neutral chemical formula
Ca₃(PO₄)₂
For 2H₂ + O₂ → 2H₂O, how many moles of H₂O form from 3 mol H₂ with excess O₂?
3 mol H₂O
What volume of 1.5 M solution contains 0.30 mol solute?
0.20 L or 200 mL
Complete and write the balanced neutralization equation for Ca(OH)2+HNO3→
Ca(OH)2+2HNO3→Ca(NO3)2+2H20
Acidic soil is treated with CaCO₃ (limestone). What is the main chemical purpose of adding limestone?
To neutralize acidity / increase soil pH
Element X has isotopes of mass 24 (79%) and 25 (21%). Estimate its average atomic mass.
24.21 u
A compound contains Cu²⁺ ions and PO₄³⁻ ions.
Cu₃(PO₄)₂ — copper(II) phosphate
CaCO₃ → CaO + CO₂. How many grams of CO₂ form from 50.0 g CaCO₃? Use M(CaCO₃)=100 g/mol and M(CO₂)=44 g/mol.
22.0 g CO₂
A 100 mL sample of 2.0 M solution is diluted to 500 mL. What is the new molarity?
0.40 M
25.0 mL of 0.20 M HCl reacts completely with NaOH. How many moles of NaOH are required?
0.0050 mol NaOH
25.0 mL of 0.20 M NaOH completely neutralizes 50.0 mL of an acidic food sample containing a monoprotic acid (HA). What is the molarity of the acid?
0.10 M HA