The moles of hydrogen which are produced from 57.5 grams of lithium is 8.21 grams.
<h3>What is stoichiometry?</h3>
Stoichiometry of the reaction gives idea about the relative amount of product produced by the reactant in terms of moles.
Given chemical reaction is:
2Li(s) + H₂O(l) → 2LiOH(aq) + H₂(g)
Moles of lithium will be calculated as:
n = W/M, where
- W = given mass = 57.5g
- M = molar mass = 7g/mol
n = 57.5 / 7 = 8.21 mol
From the stoichiometry of the reaction:
- 2 moles of Li = produces 1 mole of H₂
- 8.21 moles of Li = produces 8.21/2=4.105 moles of H₂
Mass of H₂ = (4.105mol)(2g/mol) = 8.21g
Hence required mass of hydrogen gas is 8.21g.
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Heat capacity is the ability of a material to store heat, higher the heat capacity higher the amount to heat stored by the material. Heat transfer usually varies inversely with heat capacity, i.e heat transfer will decrease with increase in heat capacity and vice versa. Thermal diffusivity is the ratio of thermal conductivity to the heat capacity, it says how fast (or slow) heat is transferred inside a material. Usually thermal diffusivity is directly proportional to the heat transfer rate, since heat capacity appears on the denominator, heat transfer is inversely proportional to the heat capacity.
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Energy needed : Q = 1105.5 J
<h3>Further explanation</h3>
Given
mass = 55 g
Temperature from -10°C to 0°C
Required
Energy
Solution
Heat can be calculated using the formula:
Q = mc∆T
Q = heat, J
m = mass, g
c = specific heat, joules / g ° C
∆T = temperature difference, ° C / K
Input the value :
Q = 55 g x 2.01 J/g ° C x (0-(-10))
Q = 1105.5 J