Chemistry year 11 bonding questions?
The copper will heat up to body temperature firstAluminium has more than twice the specific heat capacity of copper, so it takes more than twice as much heat to heat it up as it does to heat the copperSince they are both taking in heat at the same rate, the temperature of the copper will rise at about twice the rateAluminium 0.9 Joules per gram per degree rise (Celsius or Kelvin) Copper 0.4 Joules per gram per degree rise.
This is a good example of the risk of not doing one's science and in asking for answers on a public forum like this! Sorry, no offence meant The problem needs to be approached a little differentlyThey both can't take up heat at the same rateWhy, their thermal conductivities are differentAnd since their specific heats are also different, that adds another variable, Off hand I don't have the data of thermal conductivity and specific heat for both the metals and so cann't give you answer, but I hope you understand how to approach the question.
copper will warm up first even though they take up heat at the same rateThe prickly issue is what is meant by take up heat you could read it to mean their temperature will rise at the same rate (resulting in a tie) or that they absorb heat energy at the same rate thus Cu warms up firstThe structure of the metal is what determines heat capacityWIth a much heavier nucleus copper has fewer atoms in a gram than Aluminum hence its easier to get them to vibrate (which is heat, don't you know)Per atom, copper takes much more energy, but per gram, aluminum doesas far as One WHo KnowsSorry, he is assuming that the conductivity is the rate limiting parameter rather than, say, the warmth of the hand (blood circulation)He is right that if everything else were equal (in an identical environment) the one with the largst conductivity would heat up fasterBut the problem says they heat at the same rate hence the environment can't be the same because their conductivities ARE different.
Jordan has the basics covered, however there are some corrections needed for the first question: Firstly, a substance doesn't necessarily need free electrons to carry electricity, only freely moving charged particles - either electrons OR ions Secondly, molten sodium chloride is not a 'solution' - this implies that water is present, and the sodium chloride is dissolved in the waterAdditionally, sodium chloride is ALREADY made up of sodium ions and chloride ions - they are bonded together as their opposite charges make them attracted to one anotherMelting sodium chloride does NOT cause ions to form as the ions are already presentit merely breaks the bonds holding those ions in a fixed placeThis allows the ions to move and thus carry a charge Thirdly, aluminium metal isn't made up of electrons around aluminium nuclei - this is a better description of an aluminium atomAluminium metal is made up of positively charged aluminium IONS and delocalised electronsMetals usually prefer to give their electrons to non-metals in order to become stable, but if no non-metal atoms are available they simply 'release' or delocalise their electrons, which are then attracted to the positive charge of the metal ionHowever these electrons are also not actually fixed in place, so they can also carry a chargeThe fundamental difference between aluminium and sodium chloride is that ions carry the current in one, and electrons carry the current in the other
