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:
When the water is mixed with water at lower temperature the effective temperature of the system (i.e the water at lower temperature) will increase, thereby increasing it's entropy
Explanation:
The answer that "the entropy will is increases" is correct as:
The water at 90° C i.e at higher temperature is mixed with the water at 10° C i.e the water at the lower temperature.
The water at lower temperature will have molecules with lower energy while the water with higher temperature will have molecules undergoing high thermal collisions. Thereby, when the water is mixed with water at lower temperature the effective temperature of the system (i.e the water at lower temperature) will increase, thereby increasing it's entropy.
Therefore, the answer is correct with respect to the water at lower temperature.
Meanwhile, for the water at higher temperature , the temperature of the system will decrease. Thus, the entropy of the water at higher level will decrease.
Molarity of Ag+ is less than the molar solubility thus ppt will not occur.
Balanced reaction-:
<h3>2AgNO3(aq)+K2CrO4(aq)→Ag2CrO4(s)+2KNO3(aq)</h3>
Moles of AgNO3=mass(g)molar mass (g/mol) =2.7×10−5g / 169.86 gmol
=1.589⋅10^−7 mol
Molarity of Ag+=moles of solute(L)=1.589⋅10−7 mol0.015 L=1.059⋅10−5M
Ksp of Ag2CrO4
=[Ag+]2[CrO42−]
1.2⋅10−12=[2s]2[s]
4s3=1.2⋅10−12
s=6.69⋅10−5 M
Molarity of Ag+ is less than the molar solubility thus ppt will not occur.
<h3>What is the molarity calculation formula?</h3>
The volume of solvent required to dissolve the provided solute is multiplied by the ratio of the moles of the solute whose molarity has to be computed. (M=frac{n}{V}) The molality of the solution that needs to be computed in this case is M. n is the solute's molecular weight in moles.
Learn more about Molarity:
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Entropy is a measure of chaos or disorder in a system. For the first one, the system with the highest entropy is a cup of water at 0 degress centigrade. For the second question, the system with the lowest entropy is sugar crystals in 95 degrees centigrade cup of coffee.
