P6 - Molecules and Matter Flashcards
What is the formula for density
Density (g/cm cubed ) = mass(g)/ volume (cm cubed)
A block of wood has a density of 0.8 g/cm3. The block measures
30 cm x 10 cm x 10 cm. Calculate the mass of the block of wood in kg.
0.8 = mass /3000
0.8 × 3000 = mass
2400 g = mass
How would you determine the voloume of an irregular object ?
Fill a measuring cylinder so that there is enough water to cover the object when it is placed inside the cylinder. Take the reading of the volume.
Carefully lower the object into the cylinder.
Take the new reading of the volume. Subtract the original reading to obtain the volume of the object.
Explain the difference in density between the different states of matter in terms of the arrangement of atoms and molecules
Solid - compact, rigid, jose mourinho defence
Liquid - are close ,no regular arrangement, darians sisters bunda
Gas -well separated with no regular arrangement
What is density?
Mass per unit volume of a substance
How do you measure the density of a solid object or a liquid?
Measure its mass and its volume, then use the density equation p = m/v
What happen to objects when they have a lower density than water (i.e., <1000kg/m3)
They float in water
Steam machines are used to sterilise kitchen work surfaces.
The latent heat of vaporisation for water is 2.26x10^6 J/kg. Calculate the energy needed to change 60 g of water into steam.
Using the formula (thermal energy for a change of state = mass x specific latent heat)
0.06 kg x 2.26 x 10^6 = 135600 joules
Give one reason why the temperature of the solder joint remains constant as the liquid solder becomes solid.
the solid actually loses some energy when these molecules escape. This keeps the temperature from rising beyond the boiling point. As heat energy is added, more molecules escape, and the temperature remains relatively constant.
what is the process called from a gas to a solid
Deposition
what is the process called from a solid to a gas ?
Sublimation
what is the process called from a gas to a liquid
Condensation
What is boiling point?
The temperature at which a pure substance boils or condenses
What is freezing point?
The temperature at which a pure substance freezes
What is internal energy?
The energy of the particles of a substance due to their individual motion and positions
What is latent heat?
The energy needed for a substance to change state but not the tempreture.
What is the melting point?
The temperature at which a pure substance melts or freezes (solidifies)
What is physical change?
A change in which no new substances are produced
What is pressure and the unit?
force per unit cross-sectional area for a force acting on a surface at right angles to the surface. The unit of pressure is the pascal (Pa) or newton per square metre (N/m2)
What is specific latent heat of fusion Lf?
energy needed to melt or freeze 1 kg of a substance with no change of temperature
What is specific latent heat of vaporisation Lv?
energy needed to evaporate or condense 1 kg of a substance with no change of temperature.
What is Boyles law?
Boyle’s law is a gas law, stating that the pressure and volume of a gas have an inverse relationship. If volume increases, then pressure decreases
What is the change of state when wax turns from a solid to a liquid
It is melting
What is the change of state when a gas turning back into a liquid?
Condensation
