Answer : The value of
for the reaction is +571.6 kJ/mole.
Explanation :
According to Hess’s law of constant heat summation, the heat absorbed or evolved in a given chemical equation is the same whether the process occurs in one step or several steps.
According to this law, the chemical equation can be treated as ordinary algebraic expression and can be added or subtracted to yield the required equation. That means the enthalpy change of the overall reaction is the sum of the enthalpy changes of the intermediate reactions.
The given chemical reaction is,

Now we have to determine the value of
for the following reaction i.e,

According to the Hess’s law, if we reverse the reaction then the sign of
change.
So, the value
for the reaction will be:


Hence, the value of
for the reaction is +571.6 kJ/mole.
Mass = mr x moles
Mr of CuCl2 = ( 63.5) + ( 35.5 x 2) = 134.5
2.5 = 134.5 x moles
2.5 / 134.5 = moles
Moles = 0.019 (2DP)
0.25g of Al
Mr of Al = 27
0.25 = 27 x moles
0.25/ 27 = 0.0093 moles (2sf)
Hope this helps :)
You just need to multiply the total mass by the decimal value of the part that is tin. 133.8*0.103=13.8g (following the rules of significant figures).
The earth's plates usually move in three different ways resulting in three different types of plate margins/ boundaries:
CONVERGENT, DIVERGENT and TRANSFORM plate boundaries.When plates move towards each other, they collide and this usually either results in the denser of the plates sliding below the other plate or both plates pushing against each other resulting in both plates being pushed upwards to form often times Fold Mountains. This type of earth tectonics causes a CONVERGENT (destructive; because the collision of the plates results in loss of earth surface area) plate boundary to be formed.
Plates can also pull away from each other and in so doing creating space usually in the form of a fissure between the two moving plates. This fissure usually also for molten earth (magma) rising to the surface and closing the opening between the plates. This type of earth tectonic is known to form DIVERGENT (constructive; because it usually results in new land being formed) plate margins.
Plates also slide against each other (side to side) thus not resulting in neither the destruction or creation of new land. This kind of plate margin is known as the TRANSFORM plate boundary.
The diagram below helps to solidify the points made above.