Chemistry: Chapter 3

Calorie

Definition of Calorie. The amount of heat required to raise the temperature of one gram of water from 14.5°C to 15.5°C. 1 calorie = 4.184 joules.

Joule

Definition of Joule. A unit of energy in the SI system. One joule is 1 kg. m2/s2 which is also 0.2390 calorie.

Energy

Energy is defined in science as the ability to do work. It is a scalar physical quantity. Although energy is conserved, there are many different types of energy, such as kinetic energy, potential energy, light, sound, and nuclear energy.

Conversion factor

A conversion factor is a ratio (or fraction) which represents the relationship between two different units. A conversion factor is ALWAYS equal to 1.

Temperature

A measure of the intensity of heat, i.e. the hotness or coldness of a sample. or object.

Scientific notation

A method of writing or displaying numbers in terms of a decimal number between 1 and 10 multiplied by a power of 10.

Celsius scale

Celsius Temperature Scale Definition: The Celsius temperature scale is a common but non-SI temperature scale which is defined by assigning the temperatures of 0°C and 100°C to the freezing and boiling points of water, respectively.

Significant figures

Chemistry is a very vast field. Chemistry is divided into a number of branches such as Organic chemistry, Inorganic chemistry, Physical chemistry, biochemistry, Applied chemistry, Nuclear chemistry etc. Significant Figures. Significant figures are the reliable digits in a number or measurement.

Key Equations

Error= experimental value- accepted value Percent error= IerrorI/accepted value x 100% K= C+273 and C=K-273 1 J=0.2390 cal and 1 cal=4.184 J Density=mass/volume

A plastic ball with a volume of 19.7 cm to the third has a mass of 15.8 g. Would the ball sink or float in a container of gasoline?

It would sink because the density of the ball, 0.802 g/cm3, is greater than the density of gasoline.

Kelvin scale

Kelvin is a temperature scale designed so that zero degrees K is defined as absolute zero (at absolute zero, a hypothetical temperature, all molecular movement stops - all actual temperatures are above absolute zero) and the size of one unit is the same as the size of one degree Celsius.

How do measurements relate to experimental science?

Measurements are fundamental to the experimental sciences. For that reason, it is important to be able to make measurements and to decide whether a measurement is correct.

Which five SI base units are commonly used in chemistry?

Meter(m), kilogram(kg), kelvin(K), second(s)

Precision

Precision refers to the closeness of two or more measurements to each other. Using the example above, if you weigh a given substance five times, and get 3.2 kg each time, then your measurement is very precise. Precision is independent of accuracy.

Measurement

Prefix used in the SI system meaning "multiply by 10-18". For example, 3 am means 3× 10-18 meters. base unit. Base units are units that are fundamental building blocks in a system of measurement. There are seven base units in the SI system.

Density

The density of a substance is the relationship between the mass of the substance and how much space it takes up (volume). The mass of atoms, their size, and how they are arranged determine the density of a substance.

Which metric units are commonly used to measure length, volume, mass, temperature, and energy?

The five SI base units commonly used by chemists are the meter, the kilogram, the kelvin, the second, and the mole. What metric units are commonly used to measure length, volume, mass, temperature and energy? In SI, the basic unit of length is the meter (m).

What determines the density of an object?

The mass of atoms, their size, and how they are arranged determine the density of a substance. Density equals the mass of the substance divided by its volume; D = m/v. Objects with the same volume but different mass have different densities.

Absolute zero

The zero point on the absolute temperature scale; -273.15°C or 0 K; theoretically, the temperature at which molecular motion ceases.

State the difference between mass and weight.

There is a basic difference, because mass is the actual amount of material contained in a body and is measured in kg, gm, etc. Whereas weight is the force exerted by the gravity on that object mg. Note that mass is independent of everything but weight is different on the earth, moon, etc.

How are accuracy and precision evaluated?

To evaluate the accuracy of a measurement, the measured value must be compared to the correct value. To evaluate the precision of a measurement, you must compare the values of two or more repeated measurements.

Weight

Weight is the name of the force exerted on an object due to the acceleration of gravity. The weight is equal to the mass times the acceleration due to gravity (9.8 m/sec2 on Earth).

Error

a discrepancy between a computed, observed, or measured value or condition and the true, specified, or theoretically correct value or condition.

Percent error

a measure of how innaccurate a measurement is, standardized to how large the measurement is. It is the relative error expressed in terms of per 100. The relative error is calculated as the absolute error divided by the magnitude of the exact value.

Accuracy

a measurement is how close a result comes to the true value. Determining the accuracy of a measurement usually requires calibration of the analytical method with a known standard.

Kilogram

a unit of mass equal to 1000 grams: the basic unit of mass in the International System of Units (SI), equal to the mass of the international prototype of the kilogram, a platinum-iridium cylinder kept in Sèvres, France. Abbreviation: kg

Dimensional analysis

analysis using the fact that physical quantities added to or equated with each other must be expressed in terms of the same fundamental quantities (such as mass, length, or time) for inferences to be made about the relations between them.

Liter

liter - a metric unit of capacity, formerly defined as the volume of one kilogram of pure water under standard conditions; now equal to 1,000 cubic centimeters (or approximately 1.75 pints) cubic decimeter, cubic decimetre

Meter

meter is the basic unit of length in the SI system of units. The meter is defined to be the distance light travels through a vacuum in exactly 1/299792458 seconds. Meters are abbreviated using a lower case "m" in measurements. 1 m is about 39.37 inches.

Accepted value

the accepted value denotes a value of a substance accepted by almost all scientists and the experimental value denotes the value of a substance's properties found in a localized lab.

Experimental value

the accepted value denotes a value of a substance accepted by almost all scientists and the experimental value denotes the value of a substance's properties found in a localized lab.

International System of Units

the unit system adopted by the General Conference on Weights and Measures in 1960 and recommended for use in all scientific and technical fields. It consists of seven base units (meter, kilogram, second, ampere, kelvin, mole, candela), plus derived units and prefixes.