Name: Manganese
Symbol: Mn
Atomic Number: 25
Atomic Mass: 54.93805 amu
Melting Point: 1245.0 °C (1518.15 K, 2273.0 °F)
Boiling Point: 1962.0 °C (2235.15 K, 3563.6 °F)
Number of Protons/Electrons: 25
Number of Neutrons: 30
Classification: Transition Metal
Crystal Structure: Cubic
Density @ 293 K: 7.43 g/cm3
Color: silverish/grayish
An LED is useful because when a current passes through it, it gives out light.
Answer:
C
Explanation:
To melt the alcohol
Heat needed = M . L = 2 . 25 = 50 kcal
To warm up the alcohol
Heat needed = M . sp. ht. . ∆t = 2 . 0.6 . 100 = 120 kcal
Total heat needed = 170 kcal
Assuming that 0.6 kcal/ kg / ˚C is the specific heat and that the answer is wanted in kcal ( a rather odd unit to be in use here.)
If the heat change of the surroundings (such as the solution the reaction is occurring in) is determined to be 2.7 kJ, what is the heat change of the reaction (qrxn)?
Answer: First of all we can conclude that this is an exothermic reaction. The reason being that an exothermic reaction is one that produces a temperature increase in a isolated system giving off heat to the surroundings. Therefore the heat of the reaction is a negative quantity (qrxn < 0).
I hope it helps, Regards.
