Answer:
There are five evidences that tell whether a chemical change has occurred. These are change of color, change of odor, change in temperature or energy, formation of gas and formation of a precipitate.
Explanation:
Chemical Change- This is a type of chemical reaction which occurs when the properties of one or more atoms change and results into a<u> newly formed substance. </u>
Let's have a further discussion of the evidences.
1. Change of Color- Color change is caused by the combination of two or more substance with different molecular structures. A popular example of this is the Statue of the Liberty, which is made of copper plates. Due to the exposure of copper to elements like water, it changed color.
2. Change of Odor- This can be best presented with rotting food. During the rotting process, the food undergoes a chemical reaction. The result is a rotten smell.
3. Change in Temperature or Energy- An example of this is the burning of wood. Its change is considered non-reversible.
4. Formation of Gas- This can be best presented with the cake batter (the one being used to make cakes or pancakes). The batter rises which means it is forming gas. This is caused by the reaction of the baking soda and the acid.
5. Formation of a Precipitate- This occurs when two soluble salts combine and their outcome is an insoluble salt (this is the precipitate).
Take note that if any of these evidences occur, then there's definitely a chemical reaction.
Answer:
Explanation:
The Ce metal has electronic configuration as follows
[Xe] 4f¹5d¹6s²
After losing 4 electrons , it gains noble gas configuration ,. So Ce ⁺⁴ is stable.
Eu has electronic configuration as follows
[ Xe ] 4 f ⁷6s²
[ Xe ] 4 f ⁷
Its outermost orbit contains 2 electrons so Eu²⁺ is stable. Its +3 oxidation state is also stable.
Ce⁺²
Answer:
1200 mL
Explanation:
Given data
- Initial pressure (P₁): 600.0 mmHg
- Initial volume (V₁): 400.0 mL
- Final pressure (P₂): 200.0 mmHg
For a gaseous sample, there is an inverse relationship between the pressure and the volume. If we consider the gas as an ideal gas, we can find the final volume using Boyle's law.
Answer:
Mass = 64 g
Explanation:
Given data:
Mass of water produced = 36 g
Mass of oxygen needed = ?
Solution:
Chemical equation:
CH₄ + 2O₂ CO₂ + 2H₂O
Number of moles of water produced:
Number of moles = mass/molar mass
Number of moles = 36 g/ 18 g/mol
Number of moles = 2 mol
Now we will compare the moles of water and oxygen.
H₂O : O₂
2 : 2
Mass of oxygen:
Mass = number of moles × molar mass
Mass = 2 mol × 32 g/mol
Mass = 64 g
Answer:
The answer to the question is
The wave speed is 53.57 cm/s
Explanation:
The speed of a wave is the distance covered by the wave per unit time.
Wave speed is given by
v = f×λ
where v = The velocity of the wave
f = The wave frequency
λ = The wavelength of the wave
the speed v of the wave can also be expressed interms of the period as
v = λ/T
The freuency of the given wave is f = 5/(0.112 s) = 44.64 Hz and the wavelength is λ = 1.20 cm
Therefore the speed of the wave = 44.64 Hz × 1.20 cm = 53.57 cm/s
