In physics, power is the rate of doing work. It is the amount of energy consumed per unit time. Having no direction, it is a scalar quantity. In the SI system, the unit of power is the joule per second (J/s), known as the watt in honour of James Watt, the eighteenth-century developer of the steam engine.
Answer: 6,25 moles
Explanation: mark amount of butane x.
From equation you can calculate x in a following way:
2/x = 8/25. 8x = 50. And x = 6,25
Answer: Th enthalpy of combustion for the given reaction is 594.244 kJ/mol
Explanation: Enthalpy of combustion is defined as the decomposition of a substance in the presence of oxygen gas.
W are given a chemical reaction:



To calculate the enthalpy change, we use the formula:

This is the amount of energy released when 0.1326 grams of sample was burned.
So, energy released when 1 gram of sample was burned is = 
Energy 1 mole of magnesium is being combusted, so to calculate the energy released when 1 mole of magnesium ( that is 24 g/mol of magnesium) is being combusted will be:

Answer:
Fe(NO₃)₃ + 3KSCN → Fe(SCN)₃ + 3KNO₃
Explanation:
Chemical equation:
Fe(NO₃)₃ + KSCN → Fe(SCN)₃ + KNO₃
Balanced Chemical equation:
Fe(NO₃)₃ + 3KSCN → Fe(SCN)₃ + 3KNO₃
Type of reaction:
It is double displacement reaction.
In this reaction the anion or cation of both reactants exchange with each other. In given reaction the cation Fe⁺³ exchange with cation K⁺.
The given reaction equation is balanced so there are equal number of atoms of each elements are present on both side of equation and completely hold the law of conservation of mass.
Double replacement:
It is the reaction in which two compound exchange their ions and form new compounds.
AB + CD → AC +BD