Building a tower out of magnetic blocks and water vapor condensing on a bathroom mirror are only physical changes.
A physical change is easily reversible. It does not involve a change in the composition of a substance.
A tower built out of magnetic blocks can easily be pulled apart and water that condensed on a bathroom mirror can easily change back to vapour by heating.
All these are possible because the both processes are only physical changes.
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Answer:
Explanation:
A foam coffe cup is considered a perfectly insulated system: heat energy is not exchanged with the surroundings.
Under that assumption, the heat released by the chemical reaction is equal to the heat absorbed by the system.
1. Heat absorbed by the system:
Use the equation Heat = Q = m × C × ΔT, with:
- m = 126 g (the amount of solution produced)
- C = specific heat of pure water = 4.186 J/gºC
- ΔT = increase of temperature = 24.70 ºC - 21.00ºC = 3.70ºC
Q = 126g × 4.186J/gºC × 3.70ºC = 1,951.5J
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<em><u>2. Enthalpy of the reaction</u></em>
The enthalpy must be reported in kJ/mol.
Then, convert juoles to kilojoules, dividing by 1,000; and divide by 2.00 moles, which is the amount of compound that reacted:
- ΔHrxn = 1,951.5J × (1kJ / 1,000J) × (1 / 2mol) ≈ 0.9758 kJ/mol
Round to <em>3 significant figures</em>: 0.976 kJ/mol
Vinegar is a mixture cause its composed of water and acetic acid.
Half life is defined as the time when the final concentration reduced to half of the initial value.
Thus, for first half life, the remaining percentage of the reactant is 50 percent that is 
Now, for second half life, the remaining percentage will be 50 percent of the remaining 50 percentage that is 
or 
Thus, general formula for n half lives =
Now, 98.4 years is equal to eighth times 12.3 years that is 
=
remaining material.
Therefore, mass of the nuclide will remain after 98.4 years= 
= 
Mass of remaining nuclide after 98.4 years =
Ionize in water not dissociate
