solid, liquids and gases Flashcards
Order solids, liquids and gases in order of density from high to low
solids, liquids, gases
What is density?
density = mass / volume
ρ = m/V
What can density be measured in?
kg/m³ or g/cm³
What do you use to measure a regular solid?
a half-metre rule
How do you measure the volume of a liquid displaced by an irregular solid?
make sure the measuring cylinder is on a flat surface and you look at the scale straight on to avoid parallax error
How do you measure the volume of an irregular solid?
measure mass using weighing scales, put in a displacement can and measure the volume of liquid displaced
What is pressure?
pressure = force / area
p = F/A
What is pressure measured in?
pascals
What is force measured in?
newtons
What is area measured in?
square metres
Why does a stiletto or pin have more ability than your thumb?
all the pressure is concentrated on one point
How does pressure in liquids act?
equally in all directions (as long as it isn’t moving)
What is the pressure exerted on humans by the atmosphere?
about 100 000 Pa
What is the formula for pressure difference?
pressure difference = height x density x gravitational field strength
h x ρ x g
How do you convert from g/cm³ to kg/m³?
multiply by 1000
What is pressure?
weight in newtons per metre squared acting down on a surface
1 Pa = ?
1 N/m²
What is the process from solid to liquid?
melting
What is the process from liquid to gas?
boiling
What is the process from gas to liquid?
condensation
What is the process from liquid to solid?
freezing
What is a boiling point?
when a liquid becomes a gas
What is a melting or freezing point?
when a solid becomes a liquid
Describe the structure and position of molecules in a solid substance
the molecules in a solid are tightly packed and held in fixed positions by strong forces. the molecules can vibrate around their fixed positions. as the solid gets hotter the vibrations get bigger
Describe the structure and position of molecules in a liquid substance
closely packed, irregular structure, intermolecular forces are strong, molecules move randomly
Describe the structure and position of molecules in a gas substance
widely spaced, continuous state of random motion, weak intermolecular forces except during collisions, molecules move randomly
Particles in a solid:
tightly packed, held in fixed pattern or crystal structure by strong forces, vibrate around their fixed positions
Particles in a liquid:
tightly packed, not held in fixed positions but still bound together by strong forces, move at random with no fixed positions
Particles in a gas:
very spread out, no fixed positions and the forces between them are very weak, move in a rapid random motion
What is the symbol for temperature change?
ΔT
1st gas law: The random motion of gas and liquid particles explains why…
pressure acts in all directions at any point
2nd gas law: The speed of molecules increases with temperature, so as we heat gases in a rigid container, more.
energetic collisions with the walls happen more frequently, raising the pressure of the gas
3rd gas law: The temperature of a gas in Kelvin is proportional to…
the average kinetic energy of the gas molecules
What is Boyle’s law?
that volume is inversely proportional to pressure
What is the equation for Boyle’s law?
p1 x V1 = p2 x V2
What is the equation for pressure ratio in Boyle’s law?
p1/p2 = V2/V1
What is absolute zero?
when you cool a fixed mass of gas at constant volume, its pressure drops. if you continue to cool the gas below 0 degrees Celsius, the pressure will keep dropping until the pressure is zero, and graphs predict that this will happen when the temperature is -273 degrees Celsius, and this is the lowest possible temperature. this is called 0 Kelvin (K)
What is density defined as?
The mass per unit volume of a material.
What is the equation relating density, mass, and volume?
ρ = m / V
What are the units of density when mass is in kilograms and volume is in cubic metres?
kg/m³
How does density vary between materials of different densities?
Objects made from low density materials typically have a low mass; similarly sized objects made from high density materials have a high mass.
Fill in the blank: A bag of feathers is ______ compared to the same bag full of metal.
far lighter
True or False: Gases are generally denser than solids.
False
What is the formula to calculate the volume of a rectangular object?
Volume = length × width × height
What is the formula to calculate the density of an object?
Density = mass / volume
What equipment is used to measure the mass of objects in density experiments?
Digital Balance
In the density determination of irregular objects, what technique is commonly used?
Displacement technique
What is pressure defined as?
The concentration of a force or the force per unit area.
What is the equation relating pressure, force, and area?
P = F / A
What is the unit of pressure?
Pascals (Pa)
How does the area affect pressure when a force is applied?
If a force is spread over a large area, it results in small pressure; if spread over a small area, it results in large pressure.
What happens to pressure as depth increases in a fluid?
The pressure exerted increases with depth.
What is the equation for pressure difference in a fluid at different depths?
P = h × ρ × g
What does ‘h’ represent in the pressure equation?
Height or depth of the fluid column above the object in metres.
What is the gravitational field strength on Earth in N/kg?
9.8 N/kg
Fill in the blank: A higher pressure is exerted on an object in a fluid as its ______ increases.
depth
In the context of pressure, what is a common application of using large tyres on tractors?
They spread the weight over a large area, reducing pressure.
What is the effect of using sharp pointed ends on nails in terms of pressure?
It concentrates the force, creating a large pressure over a small area.
What should you do to minimize random errors during the density measurement of liquids?
Take repeat readings and calculate an average.
Why is it important to zero the digital balance before measuring mass?
To ensure accurate mass measurements.
What safety consideration should be taken when handling glassware in experiments?
Handle it carefully to avoid breakage and potential injury.
True or False: The pressure exerted by a fluid on an object is not uniform across the object’s surface.
False
What is the relationship between pressure and the area of a shoe in terms of high heels versus flat shoes?
High heels produce higher pressure due to their smaller area.
What is the kinetic theory of gases?
The kinetic theory of gases states that molecules in a gas are in constant random motion at high speeds.
What is Brownian motion?
Brownian motion is the random motion of tiny particles in a fluid caused by collisions with smaller invisible particles.
How is pressure defined in gases?
Pressure is defined as the force per unit area (p = F/A), where p is pressure in pascals (Pa), F is force in newtons (N), and A is area in square meters (m²).
What happens to gas pressure when the temperature decreases?
As the temperature of the gas decreases, the pressure on the container also decreases.
What is absolute zero?
Absolute zero is the temperature at which the molecules in a substance have zero kinetic energy, equal to -273 °C or 0 K.
What is the Kelvin temperature scale based on?
The Kelvin temperature scale begins at absolute zero, where 0 K is equal to -273 °C.
Fill in the blank: The temperature of a gas is a measure of the _______ of the molecules.
average speed
What is the relationship between temperature and kinetic energy in gases?
The Kelvin temperature of the gas is proportional to the average kinetic energy of the molecules.
What does Boyle’s Law state?
Boyle’s Law states that for a fixed mass of gas at constant temperature, pressure and volume are inversely proportional (pV = constant).
True or False: At constant temperature, increasing the volume of a gas decreases its pressure.
True
What is the pressure law?
The pressure law states that if the volume of an ideal gas is constant, then pressure is proportional to temperature (P ∝ T).
What happens to the pressure of a gas when its temperature increases at constant volume?
The pressure of the gas increases due to more frequent collisions with the container walls.
What is the formula for converting Celsius to Kelvin?
T/K = θ/°C + 273
What is the internal energy of a gas?
The internal energy of a gas is the sum of the kinetic energy of all the molecules.
Fill in the blank: At absolute zero, particles will have ______ movement.
no net
What happens to the average kinetic energy of molecules when a liquid evaporates?
The average kinetic energy per molecule decreases as higher-energy molecules escape from the surface of the liquid.
What is the relationship between pressure and volume for a fixed mass of gas at constant temperature?
Pressure increases when the gas is compressed and decreases when the gas is expanded.
What is the formula to compare initial and final pressures and volumes in Boyle’s Law?
p1V1 = p2V2
What is the effect of heating a gas on its pressure at constant volume?
Heating a gas increases its pressure due to increased molecular speed and frequency of collisions.
Fill in the blank: The higher the temperature, the ______ the average kinetic energy of the molecules.
higher
True or False: A temperature in Kelvin can be a negative value.
False
What does a vacuum pump do in relation to gas laws?
A vacuum pump removes air from a sealed container, demonstrating changes in volume due to pressure changes.
What is the result of compressing a gas while keeping its temperature constant?
The pressure of the gas increases.
What does an increase in temperature do to the average speed of gas molecules?
It increases the average speed of the gas molecules.
how do you convert into kelvin?
Celsius + 273
why does pressure decrease with lower temperature
MP1. (reduction in temperature) reduces
speed/KE of particles;
MP2. idea of fewer collisions with walls per unit
time;
MP3. idea of each collision with wall being less
‘hard’;
MP4. force (per unit area) on the container
decreases;
