20600Cal
Explanation:
Given parameters:
Mass of water = 319.5g
Initial temperature = 35.7°C
Final temperature = 100°C
Unknown:
Calories needed to heat the water = ?
Solution:
The calories is the amount of heat added to the water. This can be determined using;
H = m c Ф
c = specific heat capacity of water = 4.186J/g°C
H is the amount of heat
Ф is the change in temperature
H = m c (Ф₂ - Ф₁)
H = 319.5 x 4.186 x (100 - 35.7) = 85996.56J
Now;
1kilocalorie = 4184J
85996.56J to kCal; 
= 20.6kCal = 20600Cal
learn more:
Specific heat brainly.com/question/3032746
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Answer:
6.2 g
Explanation:
In a first-order decay, the formula for the amount remaining after <em>n</em> half-lives is
where
<em>N</em>₀ and <em>N</em> are the initial and final amounts of the substance
1. Calculate the <em>number of half-lives</em>.
If 
2. Calculate the <em>final mass</em> of the substance.
Answer:
Explanation:
Hello,
In this case, given the described concept regarding the Avogadro's number, we can easily notice that 27.0 g of aluminium foil has 6.022x10²³ atoms as shown below based on the mass-mole-particles relationship:
Notice this is backed up by the fact that aluminium molar mass if 27.0 g/mol.
Best regards.
