Answer:
Enthalpy change for the dissolution of the unknown solid = 4.6 Kj/mole
Explanation:
Using Q = m x Cs x ΔT ................................(1)
where Q = Amount of heat absorbed
m = Mass of solution
Cs = Specific heat capacity of solution
ΔT = Change in temperature
Given Density of solution = 1.20 g/ml
And volume of solution = 150 ml
Mass of solution = density x volume
= 1.2 x 150
= 180 g
From equation (1)
Q = 180 x 4.18 x 19.2 = 14446.08 = 14.4 Kj
So, ΔH of the dissolution of the unknown solid = 
= 
= 4.6 kj/mole
Answer:
0.1 moles of magnesium
Explanation:
Mg(s) + 2CH3COOH(aq) -------> Mg(CH3COO)2(aq) + H2(g)
Since the reaction is 1:2 in mole ratio,
1 mole of magnesium reacts with 2 moles of ethanoic acid
x moles of magnesium will react with 0.2 moles of ethanoic acid
2x = 0.2
x = 0.2/2 = 0.1 moles of magnesium used
Explanation:
( a )
The decomposition reaction of KClO₃ to form diatomic oxygen gas is the following way -
2 KClO₃ ( s ) -------> 2 KCl ( s ) + 3O₂ ( g )
( b )
The reaction of solid metal of Aluminum with Iodine in the following way -
2 Al ( s ) + 3 I₂ ( s ) ------> Al₂I₆ ( s )
( c )
The reaction of sodium chloride with aqueous sulfuric acid is as follow -
2 NaCl ( s ) + H₂SO₄ ( aq ) ------> 2 HCl ( g ) + Na₂SO₄ ( aq )
( d )
The reaction of phosphoric acid with potassium hydroxide , in the following way -
H₃PO₄ ( aq ) + KOH ( aq ) ------> KH₂PO₄ ( aq ) + H₂O ( l )
Answer:A) cotton
A fiber if available in trace or appropriate amount can link a suspect to a crime.Solubility is a preliminary test performed for identification of the type of fiber. In this method small amount of fiber evidence is dissolved in the suitable solvent to identify it's type. Some fibers completely get solublize in the solvent, some get partially soluble and other can only change their color or do not dissolve at all.
According to the given situation, the fiber dissolved in hydrochloric acid can be cotton. As the fibers of cotton are soft and slender and will get easily solubilize in hydrochloric acid.
