1-Propanol (CH3CH2CH20H) and water \'mix\' to form a uniform liquid When salt (N
ID: 147613 • Letter: 1
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1-Propanol (CH3CH2CH20H) and water 'mix' to form a uniform liquid When salt (Nacl) is added, however, you end up with two separate liquids. Briefly explain why adding charged particles breaks up the marriage of propanol and water (hint: as with the break-up of many relationships, attraction to an 'outsider is critical here? 2-You eat a hot pepper and feel the burning on your tongue. Water does not quench the burn at all; what is probably true about the molecule that made your tongue burn? Explain in 1-3 sentences. (Do not JUST use words like 'polar' or hydrophobic' in your answer. Be more mechanistic? 3-One morning you get into your car; you put your key in the ignition and turn it. Your car fails to turn on. Being the scientist that you are, list two hypotheses as to why. Pick one of your hypotheses (circle) and create a test for the hypothesis. Provide one prediction for each hypothesis and list a test that will allow you to distinguish betweern your two hypotheses (support one and refute the other) Hypothesis 1 Hypothesis 2 Test for hypothesis Prediction 1 Prediction 2Explanation / Answer
1)Two liquids mix with each other when their molecules can attract each other.They are called miscible liquids, while those that do not mix with each other and forms a separate layer (like oil and water) are called immiscible liquids. To be able to attract each other they have to be of the same nature, i.e, polar attracts polar molecules while non polar attracts non polar molecules.
Water is a polar molecule, meaning they have charged molecules ;one side is more positive and other side is more negative. These can form hydrogen bonds with other polar molecules. Propanol has both polar and non polar sides. Because of it's polar sides, it is possible for propanol to form hydrogen bonds with water and they mix well. But when you add salt, which is a complete polar molecule, what happens is that the salt and propanol competes with each other to get atttraction from water molecules . In effect, salt wins because it is more polar. Hence all water molecules get attracted to the salt and propanol separates as a different layer.
This is called 'salting out'.
2)The molecule in hot pepper that cause the burning sensation is called capsaicin.It is an odorless and colorless oil-like compound. When you eat hot pepper , the capsaicin compound binds to the pain receptors and heat receptors on the tongue. This causes calcium channels to open and Ca2+ flows in. This influx triggers release of neurotransmitters to the brain and the brain interprets the signal as pain and heat.
Taking water will only increase the burning sensation because these capsaicin molecules are non polar. Hence they won't bind with water molecules and instead gets spreaded causing more receptors to get activated. But eating an ice cream or drinking milk can reduce intensity because casein in milk or ice cream can form bonds with the compound and wash them away.
3)Hypothesis 1: battery is dead.
Hypothesis 2: bad ignition switch or problem with the wiring between the ignition switch and battery .
Test: Turn on the wind shield wipers and the headlights and also check for light on the instrument panel.
Prediction 1)If the windshield wipers function slowly as compared to normal and the headlights do not turn on, then the battery probably got discharged.
Prediction 2) If windshield wipers as well as the headlights work normally but there is no light on the instrument panel, then battery is working fine , but there could be problem with the ignition switch or wiring between ignition switch and battery.
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