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Final exam > Science: Acids & Alkalis > Flashcards

Science: Acids & Alkalis Flashcards

1
Q

what are natural indicators

A

some substances in nature that show different colors when they come in contact with acidic or alkaline solutions

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2
Q

give 3 examples of natural indicators

A

hibiscus pedal
grape skin
red cabbage leaf

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3
Q

how do natural indicators identify between acids and alkalis

A

extract of natural indicators have pigments. the pigments react to acidic or alkaline solutions.

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4
Q

how does hydrangea react to acids and alkalis

A

when grown in acidic soil: flower is blue

when grown in alkaline soil: flower is pink

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5
Q

what are the effects of red litmus under - water, acid and alkalis

A

distilled water; turns red
acid: turns red
alkalis: turns blue

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6
Q

what are the effects of blue litmus under - water, acid and alkalis

A

distilled water; no change
acid: turns red
alkalis: no change

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7
Q

what are the limitations of litmus papers

A

cannot test how alkali or how acidic a solution is

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7
Q

what is the purpose of the universal indicator

A

to measure the pH of substances

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7
Q

how do we use the universal indicator

A

1) add a few drops of the universal indicator to a substance

2) match the color developed to the pH color chart

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8
Q

what are the purposes of the pH values

A

to indicate the relative acidity or alkalinity

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8
Q

what is the pH range ( 0 - ? )

A

0 - 12

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8
Q

which one is acid and which one is alkali:

1) pH 0
2) pH 12

A

pH 0: acidic
pH 12: alkali

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9
Q

what is the neutral pH value

A

pH 7

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10
Q

give 4 household products that are acidic

A

orange juice
lemon juice
coffee
milk

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11
Q

give 5 household items that are alkali

A

egg white
baking soda solution
bleach
oven cleaner
drain cleaner

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11
Q

what is a pH meter

A

an electronic instrument used to measure the pH of solutions

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12
Q

what is a data logger

A

a data logger is connected to a pH sensor. it measures the pH of a solution and can even record the change in pH over a period of time

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12
Q

how do we use the pH meter

A

after calibration,

put the probe of the meter into a solution. the pH of the solution will be displayed on the screen of the pH meter

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13
Q

name all advantages of pH meter

A

more precise

more accurate

can measure pH pf solutions of all colors

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13
Q

name all advantages of universal indicator

A

less solution needed

convenient ( no calibration needed )

14
Q

name all disadvantages of universal indicator

A

cannot measure pH of dark solutions

less precise

less accurate

15
Q

name all disadvantages of pH meter

A

calibration needed

more solution needed

15
Q

why do gardeners use a soil pH meter to measure the soil pH

A

they can adjust the soil pH using certain chemicals if the pH is not suitable for their plants

15
Q

how accurate is a pH meter

A

it is accurate to 1 or 2 decimal places

16
Q

why shouldn’t we come into contact with some acidic or alkaline substances

A

because they are irritant or even corrosive, they can burn our skin and eyes

17
Q

what neutralizes excess acid in the stomach

A

antacid

18
Q

what is the ratio of acid and alkaline neutralization ( volume )

A

1:1

19
Q

what does the residue of the heated neutralized solution look like

A

small white solids, they look like tablesalt

20
Q

what has evaporated among the residue of the heated neutralized solution

A

water

20
Q

what is the solution for the reaction of table salt

A

sodium hydroxide + hydrochloric acid = sodium choloride + water

20
Q

how does tooth decay happen?

A

the bacteria in our mouths turn the sugars in food into acids which damages the surface of our teeth. thus, causing tooth decay.

21
Q

in neutralization, will the product be heavier than the reactants? how so?

A

although new substances will be formed, the mass is still conserved

conserved: remains the same (
keyword )

22
Q

how does stomach ache happen

A

our stomachs create acids to digest food. however, too much acid may irritate the stomach wall and cause a stomach ache

22
Q

how does toothpaste help with tooth decay

A

toothpaste is alkaline. it neutralizes the acids thereby helping tooth decay.

23
Q

what helps with stomach aches? how so?

A

antacid. it is alkaline, it neutralizes the acids in the stomach, thereby relieving pain.

23
Q

what help to regulate soil pH for agriculture? how so?

A

lime. it is alkaline. crops don’t grow well in acidic soil. therefore, farmers usually add lime to acidic soil, neutralizing the acids.

24
Q

what treats wasp stings? how so?

A

vinegar. wasp stings are alkaline while vinegar is acidic, it neutralizes the sting.

24
Q

what treats ant and bee stings? how so?

A

baking soda. this is because ant and bee stings are acidic and baking soda is alkaline. it neutralizes the acids

24
Q

how do we treat chemical waste before discharging it into the ocean?

A

chemical waste may contain acids or alkalis. it will harm aquatic life if directly discharged. to reduce pollution we can neutralize the waste before discharging

25
Q

what is the reaction of zinc in acids

A

1) gas bubbles given off

2) test for hydrogen: burns with a pop sound

3) hydrogen is produced

4) becomes smaller in size

26
Q

what is the reaction of magnesium in acids

A

1) gas bubbles given off

2) test for hydrogen: burns with a pop sound

3) hydrogen is produced

4) becomes smaller in size

27
Q

what is the reaction of iron in acids

A

1) gas bubbles given off

2) test for hydrogen: burns with a pop sound

3) hydrogen is produced

4) becomes smaller in size

28
Q

what is the reaction of copper in acids

A

1) gas bubbles are not given off

2) test for hydrogen: no sound produced

3) hydrogen is not produced

4) no change in size

29
Q

how do you test the reactions of metal with acids ( give experiment steps )

A

1) fill test tube with 1/5 dilute hydrochloric acid

2) rub metal with sandpaper to rid dirt and oxide

3) cover the mouth of the test tube loosely with an inverted stopper

30
Q

how do we draw conclusions from the reactions of metals with acids experiment

A

1) observe if bubbles are given off

2) slight movements mean that gas is produced 9 ( remove the stopper immediately and put a glowing splint near the mouth to test for hydrogen

31
Q

what happens to the metals when they corrode

A

the metals decrease in size

32
Q

what is the equation of reactions between acids and metals

A

metal + acid = hydrogen + salt

33
Q
A
34
Q
A

Final exam (3 decks)

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