weight of calcium 0.5g weight of water based on measured volume and accepted den

ID: 919499 • Letter: W

Question

weight of calcium 0.5g

weight of water based on measured volume and accepted density 100g

weight of reaction mix 100.5g

initial temp of water to nearest 0.2 19.6 c

final temp of the mix to neareset 0.2 27.2

difference in temp between -7.6

joules of heat evolved (show method of calculation)_________?

write the net ionic eqution for the reaction of calcium with water____________?

number of moles calcium used in the reaction___________?

number of joules of heat evolved per mole of calcium_____________?

1) heat evolved by calcium =heat absorbed by water=Q

Q=mass of water*specific heat of water* difference of temperature=m*Cw*T=100g *(4.18 6J/g C)*(7.6C)=3181.36 J

joules of heat evolved=3181.36 J

2) Ca +2H2OCa(OH)2 + H2

net ionic eqution is Ca (s) +2H2O(l) Ca2+(aq) + H2(g)

3)number of moles calcium used= mass of Ca used/atomic mass of Ca=0.5g/40 g/mol=0.0125 moles

4)number of joules of heat evolved per mole of calcium= joules of heat evolved/ total moles

=3181.36 J/0.0125 moles=254508.8 J

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