4. Chemical Formulae and Equations HODDER
暂无描述。系统推荐的高质量记忆内容，适合每天坚持背诵学习。
卡片预览 (24 张)
Define Relative Atomic Mass (Ar).
The average mass of the isotopes of an element compared to 1/12th of the mass of an atom of Carbon-12.
Define Relative Molecular Mass (Mr).
The sum of the Relative Atomic Masses of all the atoms in a molecule.
What is the Law of Conservation of Mass?
In a chemical reaction, no atoms are created or destroyed. The total mass of reactants = Total mass of products.
What is a Molecular Formula?
The actual number of atoms of each element in a molecule (e.g., C4H10).
What is an Empirical Formula?
The simplest whole number ratio of atoms of each element in a compound (e.g., C2H5).
If a reaction seems to lose mass, what usually happened?
A gas was produced and escaped into the atmosphere.
If a reaction seems to gain mass, what usually happened?
One of the reactants was a gas (like Oxygen) from the air that combined with the solid.
How do you calculate the % Mass of an element in a compound?
(Ar of element × Number of atoms) / (Mr of compound) × 100.
Symbol for Ammonium ion?
NH₄⁺
Symbol for Nitrate ion?
NO₃⁻
Symbol for Hydroxide ion?
OH⁻
Symbol for Carbonate ion?
CO₃²⁻
Symbol for Sulfate ion?
SO₄²⁻
State the chemical formula for Hydrochloric Acid.
HCl
State the chemical formula for Sulfuric Acid.
H₂SO₄
State the chemical formula for Nitric Acid.
HNO₃
State the chemical formula for Ammonia.
NH₃
State the chemical formula for Methane.
CH₄
What does the state symbol (s) stand for?
Solid
What does the state symbol (l) stand for?
Liquid
What does the state symbol (g) stand for?
Gas
What does the state symbol (aq) stand for?
Aqueous (dissolved in water)
What is the difference between 2Cl and Cl₂?
• 2Cl: Two separate chlorine atoms (not bonded). • Cl₂: One molecule of chlorine (two atoms bonded together).
Calculate the % by mass of Oxygen in CO₂. (C=12, O=16).
• Total M r = 12 + (16 * 2) = 44. • Mass of Oxygen = 16 * 2 = 32. • % = (32 / 44) * 100 = 72.7%