Chemistry

Table of elements

Triple Beam Balance

by Liz LaRosa

www.middleschoolscience.com

click here for a pdf version

Objectives:

• to learn the correct way to use a Triple Beam Balance

• to learn the parts of a Triple Beam Balance.

• to take precise measurements when finding the mass of an object

• to find the mass of known and unknown quantities

Materials:

• Film canisters labeled A - Z filled with different masses.

• Sets of Brass weights 200, 100, 50, 20, 10, 5, 2, & 1 gram

• Triple Beam Balances

Procedure:

1. Listen and watch carefully to the demonstration on how to use the Triple Beam Balance.

2. You and your partner will share a triple beam balance.

3. Check to see that the Pointer is pointing to zero.

4. If it is not, check to see that all the Riders are all the way to the left at the Zero mark.

5. Adjust the balance by turning the Adjustment Screw slowly until it points to zero.

6. Place the known brass weights onto the pan and practice measuring until you are comfortable using the balance beam. Start with the largest mass, 200 g, and work your way down to the smallest mass, 1 g.

7. Find the mass of the unknown film canisters.

8. Record canister letter and mass in Table 1.

Data:

Table 1: Mass of unknown film canisters in grams.

	Canister _____	Canister _____	Canister _____	Canister _____	Canister _____
Grams

Analysis and Results:

1. How should you hold a triple beam balance?

2. Why should your balance say zero before you place an object in the pan?

3. What canister had the largest mass? Letter _________ with _______ grams

4. Was it easier to find the mass of an object with a lot of mass or a little amount of mass? Explain.

5. Should our balance beam be renamed to a "Quadruple Beam Balance" - Explain.

Conclusion:

2 - 3 complete sentences on what you learned.

Bunsen Burner Techniques Lab

Parts

Introduction:

The Bunsen burner is used in laboratories to heat things. In order to use it safely and appropriately, it is important to know the correct steps on how to set it up and operate it. A Bunsen burner can produce 3 different types of flames:

The "coolest" flame is a yellow / orange color. It is approximately 300°C. It is never used to heat anything, only to show that the Bunsen burner is on. It is called the safety flame.	The medium flame, also called the blue flame or the invisible flame is difficult to see in a well-lit room. It is the most commonly used flame. It is approximately 500°C.	The hottest flame is called the roaring blue flame. It is characterized by a light blue triangle in the middle and it is the only flame of the 3 which makes a noise. It is approximately 700°C.

Lighting the Bunsen burner:

Step 1

The first step is to check for safety - lab coat on, long hair tied back, safety glasses on, books and papers away from the flame, apparatus set up not too close to the edge of the table...

Step 2

The second step is to look at the holes. Check that the holes are closed. The holes can be adjusted to let in more or less air by turning the collar (see photos below).

Open: Closed:

Step 3

Wait for the teacher's permission, then light the match. Some people prefer to turn the gas on and light the match after. The problem is, if the match breaks or goes out, the gas is leaking out of the tap while you get a new match.

Step 4

Light the Bunsen burner. When you have a flame from the match, turn on the gas tap. To turn it on, you must first push down, then turn the tap. This is a safety feature so the taps are not accidentally pushed open. Approach the match to the top of the Bunsen burner and it should light.

Tap closed: Tap open:

Step 5

Adjust the flame by turning the collar so that you have the appropriate flame for the experiment (usually the medium blue flame).

Step 6

During the experiment, stay vigilant so that if a problem occurs, you are ready to turn off the flame quickly. This means that you should not leave your table unattended.

Formulas

Change Equation
Select an equation to solve for a different unknown

	Solve for density
	Solve for mass
	Solve for volume

Where

d	=	density
m	=	mass
v	=	volume

Evaporation

Evaporation is the vaporization of a liquid and the reverse of condensation. A type of phase transition, it is the process by which molecules in a liquid state (e.g. water) spontaneously become gaseous (e.g. water vapor). Generally, evaporation can be seen by the gradual disappearance of a liquid from a substance when exposed to a significant volume of gas.

Factors influencing the rate of evaporation

Pressure

In an area of less pressure, evaporation happens faster because there is less exertion on the surface keeping the molecules from launching themselves.

Surface area

A substance which has a larger surface area will evaporate faster as there are more surface molecules which are able to escape.

Temperature of the substance

If the substance is hotter, then evaporation will be faster.

Density

The higher the density, the slower a liquid evaporates.

In the US, the National Weather Service measures the actual rate of evaporation from a standardized "pan" open water surface outdoors, at various locations nationwide. Others do likewise around the world. The US data is collected and compiled into an annual evaporation map. The measurements range from under 30 to over 120 inches (3,000 mm) per year.

Decantation

Decantation is a process for the separation of mixtures, carefully pouring a solution from a container in order to leave the precipitate (sediments) in the bottom of the original container. Usually a small amount of solution must be left in the container, and care must be taken to prevent a small amount of precipitate from flowing with the solution out of the container. It is generally used to separate a liquid from an insoluble solid.

Filtration

Filtration is a mechanical or physical operation which is used for the separation of solids from fluids (liquids or gases) by interposing a medium through which only the fluid can pass.

Distillation

Laboratory display of distillation: 1: A heating device 2: Still pot 3: Still head 4: Thermometer/Boiling point temperature 5: Condenser 6: Cooling water in 7: Cooling water out 8: Distillate/receiving flask 9: Vacuum/gas inlet 10: Still receiver 11: Heat control 12: Stirrer speed control 13: Stirrer/heat plate 14: Heating (Oil/sand) bath 15: Stirring means e.g.(shown), anti-bumping granules or mechanical stirrer 16: Cooling bath.

Distillation is a method of separating mixtures based on differences in their volatilities in a boiling

Distillation is a method of separating mixtures based on differences in their volatilities in a boiling liquid mixture. Distillation is a unit operation, or a physical separation process, and not a chemical reaction.

Triangles

• Meaning of triangles

• Triangle - Wikipedia, the free encyclopedia

A triangle is one of the basic shapes of geometry: a polygon with three corners or vertices and three sides or edges which are line segments. A triangle with vertices A, B, and C ...

• Geometry: Congruent Triangles - Math for Morons Like Us

Math for Morons Like Us - Geometry: Congruent Triangles ... Parallel Lines Congruent Tri. Congruent R. Tri.

• Triangle Geometry -- Triangles

A triangle is a polygon with three sides. There are of course triangles of different shapes and sizes. The applet below show triangles of many shapes and sizes.

Triangle (geometry)

Encyclopedia Article

Find | Print | E-mail

Article Outline

Introduction; Plane Triangles; Spherical Triangles

I

Introduction

Print this section

Triangle (geometr

y), geometric figure consisting of three points, called v

ertices, connected by three sides. In Euclidean plane ge

ometry, the sides are

straight line segments (see Fig. 1

). In spherical geometry, the sides are arcs of great circl

es (see Fig. 2). See Geometry; Trigonometry. The term triangle is sometimes used to d

escribe a geometric fi

gure having three vert

ices and sides that are arbitrary curves (see

Fig. 3).

II Plane Triangles Print this section A Euclidean plane triangle has three interior angles (the word interior is often omitted), each formed by two adjacent sides, as ÐCAB in Fig. 1, and six exterior angles, each formed by a side and the extension of an adjacent side, as ÐFEG in Fig. 4. A capital letter is customarily used to designate a vertex of a triangle, the angle at that vertex, or the measure of the angle in angular units; the corresponding lower case letter designates the side opposite the angle or its length in linear units. A side or its length is also designated by naming the endpoints; thus, in Fig. 1, the side opposite angle A is a or BC.

An angle A is acute if 0° < a =" 90°;">

A triangle is scalene if no two of its sides are equal in length, as in Fig. 1; isosceles if two sides are equal, as in Fig. 6; and equilateral if all three sides are equal, as in Fig. 7. The side opposite the right angle in a right triangle, HK in Fig. 5, is called the hypotenuse; the other two sides are called legs. The two equal sides of an isosceles triangle are also called legs, and the included angle is called the vertex angle. The third side is called the base, and the adjacent angles are called the base angles.

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If two sides of a triangle are of unequal size, the angles opposite are of unequal size; the larger side is opposite the larger angle. In the same way, if two angles are unequal, the sides opposite are unequal. Therefore, the three angles of a scalene triangle are of different sizes; the base angles of an isosceles triangle are equal; and the three angles of an equilateral triangle are equal (an equilateral triangle is also equiangular). The side opposite a right angle or an obtuse angle is the longest side of the triangle. see Trigonometry: Law of Sines for the exact relation between the sizes of the angles and sides of a triangle.

In any triangle, an altitude is a line through a vertex perpendicular to the opposite side or its extension, for example, DX in Fig. 8a and 8b. A median is the line determined by a vertex and the midpoint of the opposite side, AN in Fig. 9. An interior angle bisector is the line through a vertex bisecting the interior angle at the vertex, AR in Fig. 10; similarly, an exterior angle bisector bisects the exterior angle at the vertex, AV in Fig. 10. A perpendicular bisector is a line perpendicular to a side at its midpoint, HK in Fig. 11. The terms altitude, median, and interior angle bisector are also often applied to the line segment determined by the vertex and the intersection with the opposite side or its extension.

The three altitudes of a triangle meet in a common point called the orthocenter, O in Fig. 8a and 8b. The three medians meet in a point called the centroid, M in Fig. 9. The centroid divides a median through it into two segments, and the segment having a vertex as endpoint is always twice as long as the other segment. The three angle bisectors meet in a point called the incenter (I in Fig. 10), and the three exterior angle bisectors meet in three points called the excenters, U, V, W of Fig. 10. The incenter and the three excenters are centers of circles tangent to the sides or side extensions of the triangle. The three perpendicular bisectors meet in a point called the circumcenter, H in Fig. 11, which is the center of a circle passing through the three vertices.

If a, b, c are the three sides of a triangle, and h_a is the altitude through vertex A, the semiperimeter s is given by the formula s = y (a + b + c), and the area K by the formula K = yah_a = ÅÆÇÈÇÉÊ. Many other formulas interrelate the various parts of a triangle.

• Vertical angle Theorem Proofs

Vertical Angle Theorem: If two angles are vertical angles, then they have equal measures.

Given:

Statements/Conclusion	Justification
1) BEA and CED are vertical angles.	1) Given
2) and are opposite rays. and are opposite rays.	2) Definition of vertical angles
3) 1 and 3 are a linear pair. 2 and 3 are a linear pair.	3) Definition of linear pair
4) 1 and 3 are supplementary angles. 2 and 3 are supplementary angles.	4) Linear Pair Theorum
5) m1 + m3 = 180 degrees. m2 + m3 = 180 degrees.	5) Definition of supplementary angles
6) m1 + m3 = m2 + m3	6) Substitution Property
7) m3 = m3*	7) Reflexive Property
8) m1 = m2	8) Subtraction Property of Equality

* Step 7 is usually not necessary and is only included for clarification.

· Postulates

Angle Side Angle Postulate

Proving Congruent Triangles with ASA

The Angle Side Angle postulate (often abbreviated as ASA) states that if two angles and the included side of one triangle are congruent to two angles and the included side of another triangle, then these two triangles are congruent.

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Theorems and Postulates for proving triangles congruent
Hypotenuse Leg Theorem | Side Side Side | Side Angle Side | Angle Side Angle | Angle Angle Side |isosceles triangle proofs|CPCTC | indirect proof| quiz on all theorems/postulates

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Example of Angle Side Angle Proof

ABC XYZ

• Two angles and the included side are congruent
• CAB = ZXY (angle)
• AB = XY (side)
• ACB = XZY (angle)
• Therefore, by the Angle Side Angle postulate (ASA), the triangles are congruent.

Included Side

The included side means the side between two angles. In other words it is the side 'included between' two angles.

For more help click this link

Side Angle Side Postulate

Proving Congruent Triangles with SAS

The Side Angle Side postulate (often abbreviated as SAS) states that if two sides and the included angle of one triangle are congruent to two sides and the included angle of another triangle, then these two triangles are congruent.

Example 1

ABC XYZ
• Two sides and the included angle are congruent
  • AC = ZX (side)
  • ACB = XZY (angle)
  • CB = ZY (side)
• Therefore, by the Side Angle Side postulate, the triangles are congruent.

Included Angle

The included angle means the angle between two sides. In other words it is the angle 'included between' two sides.

For more help click this link

Side Side Side Postulate

Proving Congruent Triangles with SSS

The Side Side Side postulate states that if three sides of one triangle are congruent to three sides of another triangle, then these two triangles are congruent.
Example 1

ABC XYZ
• Alll 3 sides are congruent
  • ZX = CA (side)
  • XY = AB (side)
  • YZ = BC (side)
• Therefore, by the Side Side Side postulate, the triangles are congruent.

For more help click this link

Angle Angle Side Postulate

Proving Congruent Triangles with AAS

The Angle Angle Side postulate (often abbreviated as AAS) states that if two angles and the non-included side one triangle are congruent to two angles and the non-included angle of another triangle, then these two triangles are congruent.

Example of Angle Angle Side Proof (AAS)

ABC XYZ
• Two angles and a non-included side are congruent
  • CAB = ZXY (angle)
  • ACB = XZY (angle)
  • AB = XY (side)
• Therefore, by the Angle Angle Side postulate (AAS), the triangles are congruent.

For more help click this link

Hypotenuse Leg Theorem

Proving Congruent Right Triangles

The hypotenuse leg theorem states that any two right triangles that have a congruent hypotenuse and a corresponding, congruent leg are congruent triangles.
Example 1
Given AB = XZ, AC = ZY, ACB = ZYX = 90°
Prove ABC XYZ

• ABC and XZY are right triangles since they both have a right angle
• AB = XZ (hypotenuse) reason: given
• AC = ZY (leg) reason: given
• ABC XYZ by the hypotenuse leg theorem which states that two right triangles are congruent if their hypotenuses are congruent and a corresponding leg is congruent.

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The following proof simply shows that it does not matter which of the two (corresponding) legs in the two right triangles are congruent.

Example 2
Given AB = XZ, CB = XY, ACB = ZYX = 90°
Prove ABC XYZ

• ABC and XZY are right triangles since they both have a right angle
• AB = XZ (hypotenuse) reason: given
• CB = XY (leg) reason: given
• ABC XYZ by the hypotenuse leg theorem which states that two right triangles are congruent if their hypotenuses are congruent and a corresponding leg is congruent.

For more help click this link

CPCTC

Corresponding parts of congruent triangles are congruent

CPCTC is a short hand acronym for the phrase

'corresponding parts of congruent triangles are congruent'

What does CPCTC mean? It means that once we know that two triangles are congruent, we know that all corresponding sides and angles are congruent!

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How to prove triangles are congruent with SSS, SAS, AAS, and other postulates

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Remember the meaning of congruent triangles. Two triangles are congruent if all 3 sides and 3 angles of one triangle equal all 3 sides and all 3 angles of the other triangle. CPCTC takes advantage of this fact. The general method is to first prove that 2 triangles are congruent and then use that knowledge to prove that a certain pair of corresponding sides or angles are congruent.

Please click this link for further explanation

Isosceles Triangle Proofs

Theorems and practice

Proofs involving isosceles triangles often require special consideration because an isosceles triangle has several distinct properties that do not apply to normal triangles. Therefore, when you are trying to prove that two triangles are congruent, and one or both triangles, are isosceles you have a few theorems that you can use to make your life easier.

Isosceles Triangle

An isosceles triangle has two congruent sides and two congruent angles. The congruent angles are called the base angles and the other angle is known as the vertex angle. BAC and BCA are the base angles of the triangle picture on the left. The vertex angle is ABC

Isosceles Triangle Theorems

The Base Angles Theorem

If two sides of a triangle are congruent, then the angles opposite those sides are congruent.

Converse of the Base Angles Theorem

The converse of the base angles theorem, states that if two angles of a triangle are congruent, then sides opposite those angles are congruent.