The reason why some water and heat are added after Mg ribbon is reacted completely with air is to remove Mg3N2 as MgO.
Combustion reaction is a reaction in which a substance is completely burnt in oxygen. Magnesium ribbon can be converted to magnesium oxide by combustion in air.
The reaction is as follows; 2Mg(s) + O2 ----> 2MgO(s)
Since air contains nitrogen, Mg3N2 is also formed. Heat and water can be added to the reaction thereby converting magnesium nitride to magnesium oxide.
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Answer:
0.06mole
Explanation:
Given parameters:
Volume of balloon = 2.5L
T = 343.5K
P = 66.7kPa; in atm gives = 0.66atm
Unknown:
Number of moles of He = ?
Solution:
To solve this problem, we use the ideal gas equation.
It is mathematically expressed as;
Pv = nRT
where p is the pressure
v is the volume
n is the number of moles
R is the gas constant
T is the temperature
0.66 x 2.5 = n x 0.082 x 343.5
n = 0.06mole
Answer: Fireworks exploding is a chemical change.
Explanation: Lighting gunpowder, and making the explosion is a chemical change.
Given is the specific heat of water equal to 4.18 Joule per gram per *C.
This means to raise the temperature of 1 g of water by 1 degree Celsius we need 4.18 joule of energy.
Now, look at the question. We are asked that how much amount of energy would be required to raise the temperature of 25 g of water by (54-50) = 4 degree celsius.
To do so we have formula
Q = m C (temperature difference)
Have a look at pic for answer