P6 : Molecules and Matter Flashcards
What is a Boyles law?
A law that states that pressure is inversely proportionate to volume AT A CONSTANT TEMPERATURE.
What is the equation for Boyles law?
P1 V1 = P2 V2
What is Charles’ Law?
A law that states that VOLUME is directly proportionate to TEMPERATURE at a CONSTANT PRESSURE
-particles gain RANDOM KINETIC ENERGY
Meaning of density.
Density is the measure of the amount of mass in a volume.
Density equation.
Density = Mass/volume kg/m3 = kg / m3
What is the density of water?
1g/cm3
What is pressure?
Pressure is the force acting on an area.
Pressure equations.
Pressure = force/ area N/m2 = N / m2
Explain why atmospheric pressure decreases with increasing altitude. (3)
- At increased altitudes there are fewer molecules
- So the force acting down is less, decreasing pressure - less weight of molecules
- less particles colliding with a surface
Describe a method to work out the density of an irregular object’s density. (7)
- Measure the object’s mass on an electronic balance
- Tie a string around the object
- Fill a eureka can with water
- Place a measuring cylinder under the eureka can
- Drop the object in the eureka can so it is fully immersed and water should be displaced
- Read the volume of water displaced on the measuring cylinder and this is the volume of the irregular object in cm3
- Use density= mass/volume to work out the density of the object
what is LUSACC’S LAW?
- AS TEMP INCREASES, PRESSURE INCREASES
- particles gains KE and move faster
- collide with sides of container MORE OFTEN, with MORE ENERGY
- so pressure increases
what is INTERNAL energy and the 2 types?
- ENRGY INSIDE OBJECT
- BOND ENERGY - energy of intermolecular forces holding particles together
- HEAT - random kinetic energy of particles
why can gases/liquid be poured but not solids?
- WEAKER INTERMOLECULAR FORCES
- particles are FREE TO MOVE
- Solids have stong IM forces, holding particles in place
difference between BOILING AND EVAPORATION?
- EVAPORTATION - molecules escape SURFACE
- happen at any temp
BOILING - entire volume vaporising
what is specific latent heat?
- amount of energy needed to CHANGE THE STATE OF 1KG of a substance WTHOUT CHANGING TEMP.
ENERGY = MASS X SPECIFIC LATENT HEAT OF FUSION/VAPOURISATION
J = KG X J/KG
E = mL
what is absolute zero ?
-273 degrees Celsius
required practical: specific heat capacity?
- connect ammeter , power supply and heater in series, with voltmeter in parallel to block
- If the power of the heater is unknown, switch on the power supply and measure the current and potential. Calculate the power using the equation
P = IV - Keep the power supply on and start the timer. Measure the temperature of the block every 10 minutes.
- Plot a graph of temperature against work done by the heater. Calculate the gradient of the line.
- Specific heat capacity is the gradient divided by the mass of the block. Since the mass is 1kg, the inverse of the gradient = specific heat capacity of the block.
required practical : reistance and length of wire
- Set up circuit with cell, voltmer and ammeter in series and by connecting two crocodile clips to the thin resistance wire a distance of 10 cm apart and setting the power supply to 1.5 V
- Connect the wire, using the clips, to the rest of the circuit
- Record the potential difference from the voltmeter and current from the ammeter
- Move the clips in 10 cm intervals further apart
- Take new measurements from the voltmeter and ammeter for each length reading
- Continue until the crocodile clips are a length of 1 m apart
- use V=IR to find resistance
required practical : resistance in circuits
- Connect the circuit, with a battery of 4 V, first with one resistor (R1) with the voltmeter connected in parallel and ammeter in series
- Close the switch and record the reading on the voltmeter and ammeter
- Repeat steps 1 and 2 for just the second resistor (R2)
- Open the switch and add connect both R1 and R2 in series, connecting the voltmeter in parallel to both resistors
- Close the switch and record the new readings on the voltmeter and ammeter
- Open the switch and arrange R1 and R2 now in parallel shown , as well as voltmeter
- Close the switch and record the readings on the voltmeter and ammeter
- use V=IR