Answer: 14943.5 J
Explanation:
The quantity of heat energy (Q) required to raise the temperature of a substance depends on its Mass (M), specific heat capacity (C) and change in temperature (Φ)
Thus, Q = MCΦ
Given that,
Q = ?
Mass of water = 55.0g
C = 4.18 J/g°C
Φ = 65.0°C
Then, Q = MCΦ
Q = 55.0g x 4.18 J/g°C x 65.0°C
Q = 14943.5 J
Thus, 14943.5 joules of heat is needed to raise the temperature of water.
Answer:
320 g
Step-by-step explanation:
The half-life of Co-63 (5.3 yr) is the time it takes for half of it to decay.
After one half-life, half (50 %) of the original amount will remain.
After a second half-life, half of that amount (25 %) will remain, and so on.
We can construct a table as follows:
No. of Fraction Mass
half-lives t/yr Remaining Remaining/g
0 0 1
1 5.3 ½
2 10.6 ¼
3 15.9 ⅛ 40.0
4 21.2 ¹/₁₆
We see that 40.0 g remain after three half-lives.
This is one-eighth of the original mass.
The mass of the original sample was 8 × 40 g = 320 g
