Understanding Laboratory Materials and Earth Sciences
Module 2
The Material in the Laboratory
1 – What is porcelain used for? (Fig. 23)
For heating solutions to dryness. Heat until the solvent is completely eliminated.
2 – Basis of Crystallization.
It is the difference in solubilities at different temperatures.
Example: We have 100 g of water at 80 ºC, which can dissolve 60 g of substance. Now, if we have 100 g of water at 15 ºC, it can dissolve 20 g of substance. If we prepared the solution at 80 °C and left it to cool to 15 °C, 60 g – 20 g = 40 g will crystallize.
3 – What is the percentage by weight of a solution?
It is the quotient obtained by dividing the grams of substance dissolved by the grams of solution and then multiplying by 100.
23 – What is an alloy?
It is the solid solution of 2 or more metals, usually obtained by merging them.
24 – Provide two examples of alloys.
• Bronze: Copper and Tin.
• Brass: Copper and Zinc.
28 – Define volume and capacity.
Volume: Space occupied by a body.
Capacity: Measure of the internal volume of a container.
29 – What are the units of volume and capacity?
Volume: cm3
Capacity: ml / L.
Explain the volume and capacity of a test tube. (Figs. 87 and 88)
Volume: Area occupied by the probe (base and walls).
Capacity: Measure of the internal volume of the specimen.
31 – Why are the units cm3 and ml used interchangeably?
The reason is that 1 L is the volume occupied by 1 kg of water at the temperature at which its density is highest.
This volume is equivalent to 1.000028 dm3.
35 – How do you determine the size of a small body of irregular shape?
Water is introduced into the test tube and the level is noted. Then, the body is introduced into the test tube, and the rise in the water level is observed.
38 – What is parallax error? (Fig. 21)
If we look perpendicular to the scale, it will give us an error.
Example: A watch, where the bolts are not in the same plane as the scales, and if we look perpendicular to the scale, an error occurs.
39 – How do you avoid parallax error?
By facing directly across the scale.
40 – A parent teaching his 6-year-old son to read the clock says: Look at the clock on the wall and tell the time. The boy turns and says: Six-fifteen. The father corrects him: No, child, it is six-eighteen. The boy looks back, stops talking, but is not convinced. Can you clarify the doubts of the child?
The father should guide him to see the scale perpendicularly.
41 – What is density?
It is the ratio between the mass of a body and the volume it occupies.
52 – What is gravity?
It refers to the attraction between substances. It is a density ratio.
57 – What is the density of a solution?
You divide the mass of the solution by its volume.
71 – Three factors influencing the dissolution of a given solid in water (Figs. 67 and 121)
• Fragmentation.
• The contribution of heat helps dissolve.
• Movement.
72 – What is the most important characteristic of asbestos?
Its resistance to high temperatures.
73 – Uses of asbestos.
Fireproof clothing, theater decorations, etc.
74 – What is the drawback of asbestos?
It is carcinogenic.
75 – Classes of flasks.
a – Distillation (Fig. 61)
b – Flask (Fig. 60)
c – Conical (Fig. 64)
d – Kitasato (Fig. 45)
77 – Describe and draw a volumetric flask.
Long tube with a wide base.
80 – Why use each type of flask?
a – Distillation: For distilling.
b – Capacity: To prepare solutions. It should be heated beforehand, as the glass expands with heat and changes its quantity.
c – Erlenmeyer: As an aid to perform a titration. Also for heating a solution. In assessments, in addition to a burette.
81 – What type of flask should not be heated beforehand?
The volumetric flask.
82 – Why should a flask never be heated?
Because glass expands and changes its quantity.
83 – Describe and draw a water pump (Fig. 106).
Water enters from the top. On the side, it is connected to the water pump outlet. The water then flows down the drain.
84 – What is the water pump used for?
To create a vacuum in the flask.
85 – Types of filtration.
There are 2 types:
• Ordinary.
• Vacuum or reduced pressure.
86 – Tools needed for ordinary filtration.
• Funnel
• Filter paper
• Glass
• Clamp
• Stands
• Support
88 – Tools required for reduced pressure filtration.
• Kitasato
• Water jet
• Safety bottle.
90 – What is the purpose of the safety bottle?
When cutting the flow of water, the last portions of water will not go directly to the Kitasato but will go to the safety bottle, avoiding contamination of the water in the system.
91 – How do you use the funnel?
After pouring the 2 liquids into the funnel, let it rest so that the denser liquid settles below the less dense liquid. Open the stopcock of the tube, and the denser liquid will flow into the glass, gradually closing the key as the less dense liquid is separated.
92 – Meanings of the word ‘slop’.
It is the separation of the components of a mixture of immiscible liquids based on their different densities.
94 – Properties of cacodyl oxide.
• Bad smell (foul odor).
• Poisonous substance.
• Highly flammable liquid.
95 – What happened to Bunsen during his experiments with cacodyl oxide?
He could have died from arsenic poisoning and lost sight in one eye due to an explosion in the laboratory.
96 – What is a radical?
A grouping of atoms that remains unchanged during a series of chemical reactions.
97 – Give an example of a radical.
98 – Which scientists invented the spectroscope?
Bunsen and Kirchhoff.
99 – What is a rack?
A grating that allows the placement of test tubes.
100 – How should you heat a liquid in a test tube? (Figs. 110 and 111)
It should be oriented so that the opening does not point towards any person. Heat slowly to avoid boiling.
101 – Describe and draw a pipette.
A long glass tube that ends in a narrowing. It can be graduated (graduated pipette) or have a few marks (volumetric pipette).
102 – How to use the pipette.
It allows you to obtain a sample of liquid by suction, by placing a finger on the top, and to release the liquid, you let go of the finger and the liquid falls.
103 – Describe and draw a burette.
A long, narrow tube, graduated at the bottom, with a stopcock that allows the liquid to drop at the desired speed.
104 – Using the burette.
Once filled with liquid, it can be released as fast as desired by opening the stopcock.
Module 3
Seasons
1 – What is the Earth’s axis?
It is an imaginary straight line passing through the Earth’s center, around which the planet rotates. The intersection points of this line with the Earth’s surface are the poles (North and South).
2 – What do you call the movements of the Earth’s axis?
• Precession
• Nutation
3 – What is the equator?
A great circle perpendicular to the Earth’s axis that divides it into two parts called hemispheres: the Northern Hemisphere (Boreal) and the Southern Hemisphere.
4 – What are the parallels?
Smaller circles parallel to the equator, whose length decreases as we approach the poles.
5 – What are meridians?
Circles that pass through the poles.
6 – What are geographic coordinates?
They are numbers that allow us to locate any point on the Earth’s surface.
7 – What are the geographic coordinates?
• Latitude
• Longitude
8 – What is latitude?
It is the distance from a point on the Earth’s surface to the equator, measured in degrees of meridian.
• A point above the equator: North.
• A point below the equator: South.
9 – What is longitude?
It is the distance from a point on the Earth’s surface to the prime meridian, measured in degrees of the equator.
• A point to the right of the prime meridian: Longitude East
• A point to the left of the prime meridian: Longitude West.
10 – What are the latitude and longitude of Logroño?
42 º 30 ‘N, 2 º 30’ W, approximately.
11 – What is the latitude of the equator?
0 º.
12 – What is the latitude of the poles?
90 º N and 90 º S.
13 – What is the origin or prime meridian?
The prime meridian.
14 – What is the direction of the Earth’s rotation?
It is from west to east.
15 – How fast is a place on the equator rotating in km/h?
Speed of 1,666 km/h.
16 – What is the travel speed of the Earth?
30 km/s.
17 – Convert 1666 mph to km/s.
0.46 km/s.
18 – Convert 30 km/s to km/h.
108,000 km/h.
19 – What are the Tropics?
Two parallels at a distance of 23 º 27 ‘from the equator.
• One in the Northern Hemisphere: Tropic of Cancer.
• Another in the Southern Hemisphere: Tropic of Capricorn.
20 – What are the polar circles?
Two parallels at a distance of 23 º 27 ‘from the poles.
• One in the Northern Hemisphere: Arctic Circle.
• Another in the Southern Hemisphere: Antarctic Circle.
21 – What are the equinoxes?
There are two seasons (Spring and Autumn) in which the number of daylight hours and hours of darkness are equal (12 hours light and 12 hours of darkness).
22 – When are the equinoxes?
Spring Equinox: March 20 to 21.
Fall Equinox: September 22 or 23.
23 – What are the solstices?
There are two seasons (Summer and Winter) that have the highest inequality between daylight and dark hours.
In summer, there is more light or longer days, with the sun over the Tropic of Cancer.
In winter, there are shorter days, with the sun’s rays on the Tropic of Capricorn.
24 – When do the solstices occur?
Summer Solstice: June 21 or 22.
Winter Solstice: December 21 or 22.
25 – What is the ecliptic?
It is the ellipse-shaped line that describes the Earth’s orbit around the Sun.
26 – What is an ellipse?
A curved line where the sum of the distances from two points called foci is constant.
27 – What is the angle of 23 degrees 27 ‘?
It is the angle between the plane of the Earth’s equator and the plane of the ecliptic.
28 – What are the climate zones on Earth?
1. Torrid Zone.
2. North Temperate Zone.
3. South Temperate Zone.
4. Arctic Zone.
5. Antarctic Polar Zone.
29 – Set borders for climate zones on Earth.
1. Torrid Zone: Between the Tropic of Cancer and the Tropic of Capricorn.
2. North Temperate Zone: From the Arctic Circle to the Tropic of Cancer.
3. South Temperate Zone: Between the Antarctic Circle and the Tropic of Capricorn.
4. Arctic Zone: From the Arctic Circle to the North Pole.
5. Antarctic Polar Zone: Between the Antarctic Circle and the South Pole.
30 – Place the polar circles by the value of their latitudes. Get the answer mathematically.
• Arctic Circle: 66 ° 33’N
• Antarctic Circle: 66 ° 33’S.
31 – What is the angle of the terrestrial arc in the temperate zones?
43 º 6 ‘.
32 – What is perihelion?
It is the point in a planet’s orbit where it is closest to the Sun.
33 – What is aphelion?
It is the point in a planet’s orbit where it is farthest from the Sun.
34 – What is the perigee?
It is the point in the orbit of a celestial body (sun, moon, planets, etc.) that is closest to the Earth.
35 – What is apogee?
It is the point in the orbit of a celestial body (Sun, Moon, Earth, etc.) that is farthest from the Earth.
36 – What is the relationship between Earth’s perihelion and the Sun’s perigee? What is the relationship between Earth’s aphelion and the Sun’s apogee?
The distance between the Sun and Earth is the same in both cases.
37 – What is the speed of light if one hundredth of a second covers 3,000 km?
300,000 km/s.
38 – What is the value of the speed of light in km/s? What point does the speed of light represent?
299,792.5 km/s.
C.
39 – How long does it take for sunlight to reach Earth? The average distance between the Sun and the Earth is 150 million km.
8 minutes and 20 seconds.
40 – What is a light year?
It is a unit of distance, defined as the distance traveled by light in one year.
41 – What is an astronomical unit?
It is the average distance between the Earth and the Sun, approximately 150 million km.
42 – What is a parsec?
1 pc = 3.26 ly.
It is the distance from a point that establishes an angle of 1 degree between the Earth and the Sun.
43 – The planet Sedna is about 13,000 million miles from the Sun. How much is this distance in astronomical units (AU)?
87 AU.
44 – Calculate the distance in light years that separates us from the star Vega, or Alpha Lyra, knowing that the distance in miles is 257.5 × 1012. Details: one year = 31,556,926 seconds; c = 299,792 km/s.
27.2 light years.
45 – What is an eon?
It is worth a thousand million years. 1,000,000,000 years.
46 – What is the age of the Sun?
It is 5 eons, or 5,000,000,000 years.
47 – Summary table of the seasons.
Photocopy A.
48 – What three factors account for the heat of summer or the cold of winter?
1. Distance from the Earth to the Sun.
2. Duration of the day.
3. Direction or inclination of the sun.
49 – Which of the three factors that explain the heat of summer or the cold of winter has the most influence?
The direction or inclination of the sun.
50 – How does the distance from Earth to the Sun affect winter cold or summer heat? What mistake must not be committed?
The closer we are to the Sun, the more heat and higher temperatures. The farther from the Sun, the lower the temperature and colder it gets.
Do not say:
That the heat of summer is due to the approach of the Sun or the cold of winter is due to the distance from the Earth to the Sun.
51 – Make a summary table of the motions of the Earth and their consequences.
Movement around the Sun | Speed | Time | Observations (Consequences)
Translating around the Sun | 30 km/s | 1 year = 365 days | The seasons (in temperate zones)
Rotation on its axis | 1666 km/h (for a point in Ecuador) | 1 day = 24 hours | Day (light) and night (dark).
52 – What if the Earth’s axis were not tilted?
There would be no seasons, and we would have a constant Spring and Summer.
53 – In the Book of Enoch, it states that the year has 364 days. Discuss this fact.
It is possible that when Enoch lived, the year was 364 days instead of 365.
The Sun would have more material, and consequently, the Universal Law of Gravity would attract the Earth more strongly, bringing it closer to the Sun, resulting in a shorter orbit than now.
54 – How does the length of day in winter cold or summer heat change?
It logically follows that the greater the number of hours of sunlight on Earth, the greater the heat input, raising temperatures on the Earth’s surface and in the lower layers of the atmosphere. Conversely, in winter, the opposite occurs.
However, this argument is not entirely accurate; we must also consider the situation with solar lighting. The time that the South Pole and North Pole are illuminated and in darkness is also significant, with each experiencing 6 months of light and 6 months of darkness.
55 – What is the situation with solar lighting (or lack thereof) in areas near the poles?
In summer, the sun is directly overhead, and perpendicular solar radiation reaches the Earth, concentrating the radiation. In winter, the sun’s rays strike at a steep angle.
56 – How does the direction (or angle) of sunlight in winter cold or summer heat change?
Due to the tilt of the Earth’s axis, for about 6 months, sunlight shines on one pole while the other is in darkness, and then the situation reverses for the next 6 months.
57 – Examples of simple experiments to understand the influence of the three factors mentioned on winter cold or summer heat.
A candle:
• We place our hand over the flame at different distances to feel the heat (distance).
• We hold our hand over the flame for a minute to assess the heat value (duration).
• We place our hand in different positions to observe the angle (tilt).
58 – What do you know about Eratosthenes of Cyrene?
Facts about this author:
• He was an astronomer.
• A student of Archimedes.
• His contemporaries called him Beta.
• In mathematics, he is remembered for the sieve of Eratosthenes (to determine if a number is prime).
• He was the director of the Library of Alexandria.
• He calculated the size of the Earth using a stick.
• He was also a geographer, historian, and writer.
• He died at the age of 80, around 300 BC, was blind, and chose to die voluntarily.