MedicinesDrugs4 Depressants ANSWERS

Chemistry 12 (SL + HL)
Unit 6 / IB Topic D4
Medicines and Drugs - Part 4
Depressants - ANSWERS
What are depressants?
- drugs that decrease the activity of the central nervous system by interfering with the
transmission of information from one neuron to the next
- alter information flow by changing the concentration or activity of brain chemicals called
- changes in brain activity are also result in slowing down heart activity and breathing rate
Describe how the dose of a depressant relates to its effects.
low to moderate dose = calmness, relief from anxiety, relaxed muscles
(tranquilizer to sedative)
high dose = slurred speech, staggering gait, altered perception, sleep induced
(sedative to hypnotic)
extremely high dose – breathing rate slows, coma, death (lethal dose)
Discuss three social effects of the use and abuse of alcohol.
- sickness (alcoholism) – lost productivity, cost of treatment
- car accidents - due to depression of motor control functions in the brain
- violent crimes - due to loss of judgement
- family problems
State three short-term health effects of the use and abuse of alcohol.
- increased relaxation, confidence and sociablity
- loss of self-restraint, loss of judgement and concentration
- increased risk taking behaviour
- slurred speech, loss of balance
- violent behaviour possible
- dehydration due to increased urine output => “hangover” and reduced productivity
- high doses – vomiting, loss of consciousness, possible coma and death
State three long-term health effects of the use and abuse of alcohol.
- dependency (alcoholism)
- liver disease (cirrhosis of the liver)
- high blood pressure
- coronary heart disease
- permanent brain damage
- fetal alcohol syndrome
What is a “synergistic effect”? Give three examples of the synergistic effects of ethanol.
- “synergistic” = an increase in the activity of a drug when taken in combination with another drug
- aspirin + ethanol = increased stomach bleeding
- other depressants (e.g. barbituates) + alcohol = heavy sedation, possibly coma and death
- alcohol + marijuana (THC) = greater impairment of motor functions, judgement
- alcohol + opiate analgesics = reduced blood pressure, slowed/arrested breathing,
unconsciousness, coma
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Chemistry 12 (SL + HL)
Unit 6 / IB Topic D4
The breathalyser ‘blow in the bag’ test involves a motorist blowing into a bag through a tube
containing crystals of potassium dichromate, K2Cr2O7, in an acidic medium. Describe what will be
seen if the test is positive and give the two half-equations for the reaction taking place and the
overall balanced equation.
positive test: colour change from orange to green
half equations:
(ethanol to ethanoic acid)
(dichromate to Cr )
+ 14H + 6e  2Cr
+ 7H2O
Describe the action of intoximeters.
C2H5OH + H2O  CH3COOH + 4H + 4e
sample of breath passed into infrared spectrometer
ethanol in breath absorbs because of C-H bond (not O-H because that bond is also in H2O)
machine compares breath with air/reference sample with no breath;
Three common depressants are diazepam (Valium®), nitrazepam (Mogadon®) and fluoxetine
hydrochloride (Prozac®). Find their chemical structures in the IB Chemistry data booklet.
Two of them have similar structure. Which ones?
- diazepam (Valium) and nitrazepam (Mogadon)
Which parts do they have in common and which parts are different?
- common features = 2 benzene rings; diazepine structure (7 atom ring structure with 5
carbon atoms and 2 nitrogen atoms); amide group; carbon-nitrogen double bond
- differences = a chloro group on one benzene ring in Valium, but a nitro group in the
same position in Mogadon
What do all these three drugs have in common in their structure?
- 2 benzene rings
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