Heat Formulas
What is the specific heat capacity formula?
Q = m x c x ΔT
What is an element?
A pure substance made of only one type of atom (like hydrogen, oxygen, sodium)
Is melting an endothermic or exothermic process?
Endothermic (Heat is absorbed)
What subatomic particle has a positive charge?
Proton
What happens when two negative charges are brought close together?
They repel
How much energy is required to melt 250 g of ice at 0°C?
83,500 J
What does ionization mean?
The process of gaining or losing electrons to become an ion
When water freezes outside on a cold day, is heat being absorbed or released?
Released → exothermic
Where are protons and neutrons found in the atom?
In the nucleus
A balloon rubbed on hair sticks to a wall. What type of charge does the balloon gain?
Negative (gains electrons)
A student has 12.5 g of a metal that requires 1,400 J to completely melt. What is the metal’s heat of fusion?
112 Joules/Gram
Which subatomic particle remains without a charge?
Neutron
A chemical reaction feels cold to the touch. What type of reaction is occurring and why?
Endothermic — the system absorbs heat from your hand.
If an atom has 17 protons and 18 electrons, what is its charge?
-1 (anion)
Which type of heat transfer occurs when you touch a hot pan?
How much energy is needed to boil 15 g of water at 100°C?
33,900 Joules
A technique that helped scientists discover electrons
Cathode Ray Tubes
Burning methane in a Bunsen burner releases energy as light and heat. Identify the process and justify.
Exothermic — chemical energy is released into surroundings
Carbon-14 has 6 protons. How many neutrons does it have?
8 neutrons (14 – 6 = 8)
Which heat transfer method dominates inside boiling water and explain why?
Convection — warmer, less dense water rises; cooler water sinks.
How much energy is needed to raise the temperature of 50 g of water from 25°C to 45°C?
(Specific Heat Capacity for water (C) = 4.18)
4180 Joules
Opposite Charges Attract
Like Charges Repel
Coulomb's Law
A temperature graph shows a sudden drop from 30°C to 22°C during a reaction. Explain what this indicates about energy transfer and reaction type
The reaction absorbs heat from the surroundings → endothermic, causing temperature to decrease
A magnesium ion has 12 protons and 10 electrons. What is its symbol and charge, and explain why?
Mg²⁺ — it lost 2 electrons.
On a heating curve, what does a flat (plateau) section represent?
A phase change (e.g., melting or boiling).