Δ H reaction = q / n where q: amount of heat released and n is number of moles of substance.
q = m . C . ΔT where:
m = mass of substance (g)
C = Specific heat capacity (4.18)
ΔT = change in temperature = 24.25 - 23.16 = 1.09
q = 1000 x 4.18 x 1.09 = 4556 J = 4.556 kJ
number of moles (n) = Molarity (M) x Volume (L)
= 0.185 M x 0.07 L = 0.01295 mole
Δ H = q / n = - (4.556 kJ / 0.01295 mole) = -351.8 kJ / mol
Note: it is exothermic reaction (-ve sign) i.e. temperature is raised
It's not the valences electrons themselves, but the number of valence electrons that determines the chemical properties of an element
From the given choices, aluminum oxide is the only ionic
compound there. The ions present are Al3+ and O2-. Aluminum is a
chemical compound of aluminum and oxygen with the chemical formula Al2O3. It is
the most frequently happening of numerous aluminum oxides, and precisely recognized
as aluminum (III) oxide.
Hey There!:
The density is the quotient between the mass of a material and the volume occupied by it, The density can be expressed for a substance or for a mixture of substances. For example, water density in ambient conditions is equal to 1.00 g/cm3, which means that in 1 cm³ or 1 mL, there are 1.0 g of water. Therefore:
D = m / V
D = 20 g / 5 mL
D = 4,0 g/mL
hope that helps!
Converting the specific heat into kJ/kg°C, we get that the specific heat capacity is 3.52 kJ/kg°C
Now, we use the equation:
Q = mcΔT, where Q is the heat energy, m is the mass of substance, c is the specific heat capacity and ΔT is the change in temperature of the mass of substance. Substituting these values, we get:
Q = 1.4 x 3.52 x (27.45 - 28.5)
Q = -5.17 kJ
The reaction absorbs 5.17 kilojoules of energy.
