calculation of the energy needed to heat an aluminum block

not clue, based on the absence of data ...

"the heat emitter 5" ... ??

"the aluminum block" ... ??, ok, so you know the specific hear of Aluminium, but the volume of the block is important.

"at 28 degrees Celsius at a room temperature of 18 degrees Celsius" ... ok, good ... some data !

so to work out the energy required, we have the delta T (10degC) we can look up the specific heat of Aluminium, but we need the volume of the block.

and with data (Wattage) of the heater we can start to fiure out the time ...

but as the block heats it'll lose heat to the cooler environment, so we'll need more data (the surface area of the block, the irradiance of Aluminium)

"Hoffen wir mal, dass alles gut geht !"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.

The volume of the block doesn't matter as much as the ability to transfer heat to the outside air.

If the block is the shape of a cube there is one possible set of answers, such as if it is in still air. If the block is the shape of a thin foil that will be a different answer.

Overall, the factors are how easily the heat exits the aluminum, how easily the heat is distributed through the aluminum, and how easily the heat is transferred from the emitter to the aluminum, noting that in actual systems, getting the surface temperature to be uniform is nearly impossible.

agreed, but "surely" the amount of Aluminium to be heated matters ? wouldn't the specific heat be "per unit volume" ?

"Hoffen wir mal, dass alles gut geht !"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.

The mass matters if it is a transient response where the temperature of the aluminum is being changed - here the temperature is to be held constant against a heat loss. If the question was "How long to raise the temperature?" then the mass matters. In this case the material is a pass through for the energy from the heater and the room.

agreed, the question is very badly phrased/expressed. I took it to ask "how much time to increase the temperature ... ?". It could just as easily be asking "how much energy power is needed to maintain the temperature ... ?" still "surely" mass is important to both questions ?

"Hoffen wir mal, dass alles gut geht !"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.

If we are trying to change the temp then yes you need the mass, but to maintain it (per the wording of OP's question) you just need the surface area and thermal conductivity.

title of thread "calculation of the energy needed to heat an aluminum block" ... "to heat" = to change temperature.

sure, it could easily be a difficulty in translations, "ESL" maybe; sure poorly worded question in the first place.

"Hoffen wir mal, dass alles gut geht !"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.

It's probably lifted from the middle of a homework example that includes all the missing information.