Chemistry 1 (CHM 113) Lecture Notes PDF

Chemistry 1 (CHM 113) Chemistry often is called the central science because knowledge of the principles of chemistry can facilitate understanding of other sciences, including physics, biology, geology, astronomy, oceanography, engineering, and medicine. Chemistry go about research using a set of...

Chemistry 1 (CHM 113) Chemistry often is called the central science because knowledge of the principles of chemistry can facilitate understanding of other sciences, including physics, biology, geology, astronomy, oceanography, engineering, and medicine. Chemistry go about research using a set of guidelines and practices known as the scientific method, in which observations give rise to laws, data give rise to hypotheses, hypotheses are tested with experiments, and successful hypotheses give rise to theories, which are further tested by experiment. Chemistry is the study of matter and the changes that matter undergoes Matter is what makes up our bodies, our belongings, our physical environment, and in fact our universe. Matter is anything that has mass and occupies space. What is Physical Chemistry? Why do we warm ourselves by a radiator? We turn on the radiator if we feel cold and warm ourselves in front of it. We become warm because heat travels from the radiator to us, and we absorb its heat energy, causing our own energy content to rise. This explains why we feel more comfortable. The physical chemist could do nothing if nothing happened; chemists look at changes We say a physical chemist alters variables, such as pressure or temperature. Typically, a chemist causes one variable to change and looks at the resultant response, if any. Classification of Matter Chemists classify matter as either a substance or a mixture of substances. A substance is a form of matter that has a definite (constant) composition and distinct properties. Substances can be either elements (such as iron, mercury, and oxygen) or compounds (such as salt, water, and carbon dioxide). They differ from one another in composition and can be identified by appearance, smell, taste, and other properties.  Length meter m Mass kilogram kg Base SI Units Time second s Electric current ampere A Temperature kelvin k Amount of substance Mole mol Prefix Symbol Meaning Example Tetra T 1x1012 1,000,000,000,000 1 teragram (Tg) = 1 x 1012 gm Giga G 1x109 (1,000,000,000) 1 gigawatt (GW) = 1 x 106 Hz Mega M 1x106 (1,000,000) 1 megahertz (MHz) = 1 x 106 Hz Prefixes Used Kilo- k 1x103 (1,000) 1 kilometer (km) = 1 x 103 m with SI Units Centi- c 1x10-2 (0.01) 1 cnetermeter (cm) = 1 x 10-2 m Milli- m 1x10-3 (0.001) I millimeter (mm) = 1 x 10-6 m Micro- m 1x10-6 (0.000001) I microleter (mL) = 1 x 10-6 g Nano- n 1x10-9 (0.000000001) 1 nanogram (ng) = 1 x 10-9 g Pico- p 1x10-12 (0.000000000001) 1 pico second (ps) = 1 x 10-12 s Femto f 1x10-15 (0.000000000000001) 1 femto second (fs) = 1 x 10-15 s  Temperature There are two temperature scales used in chemistry. Their units are degrees Celsius (ºC) and kelvin (K). The Celsius scale was originally defined using the freezing point (0 ºC) and the boiling point (100 ºC) of pure water at sea level. Kelvin is known as the absolute temperature scale, meaning that the lowest temperature possible is 0 K, a temperature referred to as “absolute zero.” Celsius to Kelvin K = ºC + 273 Celsius to Fahrenheit ºF = (1.8 ºC) + 32 Temperature in Fahrenheit (C) = (ºF – 32) / 1.8  Physical Properties Color, melting point, boiling point, and physical state are all physical properties. A physical property is one that can be observed and measured without changing the identity of a substance For example, we can determine the melting point of ice by heating a block of ice and measuring the temperature at which the ice is converted to water. Liquid water differs from ice in appearance but not in composition; both liquid water and ice are H2O. Melting is a physical change; one in which the state of matter changes, but the identity of the matter does not change. We can recover the original ice by cooling the water until it freezes. Therefore, the melting point of a substance is a physical property. Chemical Properties The statement “Hydrogen gas burns in oxygen gas to form water” describes a chemical property of hydrogen, because to observe this property we must carry out a chemical change—burning in oxygen (combustion), in this case. After a chemical change, the original substance (hydrogen gas in this case) will no longer exist. What remains is a different substance (water, in this case).  States of Matter ❑ In a solid, particles are held close together in an orderly fashion with little freedom of motion. As a result, a solid does not conform to the shape of its container. ❑ In a liquid, particles are close together but are not held rigidly in position; they are free to move past one another. Thus, a liquid conforms to the shape of the part of the container it fills. ❑ In a gas, the particles are separated by distances that are very large compared to the size of the particles. A sample of gas assumes both the shape and the volume of its container. ❑ The three states of matter can be interconverted without changing the chemical composition of the substance. ❑ Upon heating, a solid (e.g., ice) will melt to form a liquid (water). Further heating will vaporize the liquid, converting it to a gas (water vapor). ❑ Conversely, cooling a gas will cause it to condense into a liquid. When the liquid is cooled further, it will freeze into the solid form. Molecular-level of a solid, liquid, and gas Water as a solid (ice), liquid, and gas GASES  Characteristics of Gases ❑ A sample of gas assumes both the shape and volume of its container. ❑ Gases are compressible. ❑ Gases have higher kinetic energy compared to solids and liquids. ❑ Gases form homogeneous mixtures (solutions) with one another in any proportion. ❑ The densities of gases are much smaller than those of liquids and solids and are highly variable depending on temperature and pressure.  Gas Laws ❑ The physical state of gas can be described completely with just four parameters: ❑ Temperature & Pressure & Volume & Number of moles ❑ Knowing any three of these parameters enables us to calculate the fourth. ❑ The relationships between these parameters are known as the gas laws. Volume (V) & Pressure (P) Volume (V) & Temperature (T) Volume (V) & Amount (n)