Mass is a measure of how much stuff is in something
On Earth, the weight of a 1kg bag of sugar is 10 newtons
On the Moon, the weight of the same 1kg bag of sugar is less due to lower gravity
On Jupiter, the weight of the 1kg bag of sugar would be 25newtons
Object thrown away from the Earth
Experiences a force towards the Earth due to gravity
Acceleration due to gravity
Denoted as little g, also known as gravitational field strength
On Earth, acceleration due to gravity is 10 meters per second
Gravitational field strength (g)
Also known as the gravitational field strength, it is the force needed to stop an object from falling due to gravity
Mass
A measure of the amount of stuff in an object, indicating how difficult it is to get moving or to stop it
Mass never changes; for example, mass on Earth remains the same on the Moon
Acceleration due to gravity
Measured in meters per second per second or in newtons per kilogram, as it is a force exerted on a unit mass
Finding weight using an equation
Weight = mass x gravity
Weight is the force due to gravity and depends on the masses of the two objects attracted
Weight on Earth is roughly mass times gravity, e.g., 56 kilograms times 10 equals 560 newtons
On the Moon, gravitational acceleration is 1.6 meters per second per second, resulting in a weight of 89.6 newtons
Gravitational field strength changes on the surface of different planets due to their sizes and masses
An apple with a mass of 100 grams requires a force of about one newton to prevent it from falling to Earth
Isaac Newton got the idea for gravity from observing a falling apple
Mass always stays the same, but weight can change depending on the gravitational field strength
Weight can be different on the Moon compared to Earth due to the Moon's lower gravitational field strength
Common strong acids in the laboratory
Hydrochloric acid (HCl)
Sulfuric acid (H2SO4)
Nitric acid (HNO3)
Hydrochloric acid
The most common acid in a lab
Sulfuric acid
The most importantacid in industry, used for production of agricultural fertilisers, detergents, dyes, paints, plastics, found in carbatteries, and has many more uses
Diluting strong acids in the laboratory
1. Add acid slowly-slowly, bit by bit in lots of water, never the other way around
2. Never add water to acid! The heating generated might boil the solution violently causing splattering of concentrated acid
A good phrase to remember the rule of adding acid to water: "Do not spit in acid"
Alkali
A base that is soluble in water
Alkalis
Have bitter taste and feel soapy to the touch
Many cleaning products contain alkalis, like bleach, household ammonia, and soap
Alkalis can react corrosively with other materials and can burn your skin. In the lab, they must be handled carefully and always while wearing appropriate protective clothing, such as lab coats, gloves, and safety glasses
Neutral substances
Neither acidic nor alkaline
We cannot tell if a substance is acidic, alkaline, or neutral just by looking at it. We use indicators to distinguish between the three classes of substances
What is the force holding ionic compounds together?
Electrostatic
Electrostatic attraction between the oppositely charged ions holds them together.
Ionic bonds are typically stronger than covalent bonds due to the electrostaticattraction between ions.
What are the typical characteristics of metals?
Malleable rigid, ductile, dense,
Common compounds
Water (H2O), hydrochloricacid (HCl), sulfuricacid (H2SO4), ammonia (NH3), carbondioxide (CO2), nitricacid (HNO3), and phosphoricacid (H3PO4) are common compounds widely used in industrial and biological applications.