Chapter 1 Study of Chemistry -Chemistry is the study of matter and the changes it undergoes. It is a very practical science which means that it can be used to determine stuff we do in real life. For example‚ drugs‚ food‚ etc. are made by researching the chemical properties of the substance. -Matter is anything that has a mass and takes up space -Elements are the most basic substances something can be broken down into. There are about 100 elements known to scientists right now. There may be
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1. Hydrogen Name: Hydrogen Atomic number: 1 Atomic Weight: 1.00794 grams/mole Standard state: gas at 198 K Hydrogen is the lightest Hydrogen is the lightest element. It is by far the most abundant element in the universe and makes up above 90% of Universe by weight. Hydrogen as water (H2O) is absolutely essential to life and it is present in all organic compounds. Hydrogen is lightest gas. Hydrogen gas was used in lighter-than-air balloons for transport but is far too dangerous because
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Pre Lab Questions 1. What are the basic units of length‚ mass‚ volume‚ and temperature in the SI system? Length= meters (m) Volume= kilograms (kg) Temperature= Kelvin (K) 2. What decimal power do the following abbreviations represent: a) M=10^6 b) K=10^3 c) M=10 ^-3 d) N=10^-9 e) µ=10^-6 3. What is the number of significant figures in each of the following measured quantities? a) 351 g 3 b) 0.0100 mL 4 c) 1.010 mL 4 d) 3.72 x 10^-3 cm 3 4. What is the length of a crystal
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1. Energetics si ygrene neht srucco egnahc yplahtne na fI dna )rH In an exothermic change energy is transferred from the system (chemicals) to the surroundings. The products have less energy than the reactants In an endothermic change‚ energy is transferred from the surroundings to the system (chemicals). The products have more energy than the reactants Enthalpy changes are normally quoted at standard conditions. Standard conditions are : • 1 atm pressure • 298 K (room temperature or 25oC) • Solutions
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Name: |Date:| Exp 10: Caloric Content of Food|| Your Data: |First Item|Second Item|Third Item| What Food are you using|||| |||| Mass of empty beaker|||| Mass of beaker and water|||| Net Mass of the water|||| |||| Initial mass of food and holder|||| Final mass of burnt food and holder|||| Net Mass of the burnt food|||| |||| Initial temp of the water|||| Final temp of the water|||| ∆ T in C (change in temperature)|||| Calculations: Show your numbers in the following calculation
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Assessing Sulphur Dioxide in Wine by Titration Procedure 1. Transfer 20.0 mL of wine using a pipette to each of three 250 mL conical flasks. 2. To each flask add about 12 mL of 1 M sodium hydroxide solution and allow the flasks to stand for 15 minutes. This releases the SO2 bound in complex compounds in the wine. 3. Fill a burette with standard iodine solution. Record the initial burette reading and the concentration of the solution. 4. To one flask‚ add about 10 mL of 2 M sulfuric acid
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www.igcse.at.ua ORGANIC CHEMISTRY OIL and its many useful PRODUCTS The origin of oil Crude oil is formed from organic material of the remains of plant and animal organisms that lived millions of years ago. These remains form sediments eg at the bottom of seas‚ and become buried under layers of sedimentary rock. They decay‚ without air (oxygen)‚ under the action of heat and pressure to form crude oil over millions of years. It is a fossil fuel because it is formed from
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Directions: The following questions involve more practice with radioactive decay half-life. Complete the problems to the best of your ability. This assignment is due by next WEDNESDAY‚ November 16th. 1. If 100.0 g of carbon-14 decays until only 25.0 g of carbon is left after 11 460 y‚ what is the half-life of carbon-14? a. Calculate how many half-lives have passed during the decay of the 100.0 g sample. 100 grams/2 50 grams/2 25grams…2 half lives have passed b. Solve for the half-life
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Chemistry 12 Thought lab Part 1 (Procedure) 1) 1s22s22p23s23p24s23d24p25s24d25p26s24f25d26p2 2) When ml can only equal 1‚ each energy level can have only 1 orientation so according to the exclusion principle only 2 electrons with opposite spins can be in each orbital. So in order to get to element 30 you would need to go all the way to the 6p orbitals. In other words‚ every two electrons would necessitate going to a new orbital. 1 | 1s1 | 11 | 1s2 2s2 2p2 3s2 3p2 4s1 | 21 | 1s2 2s2 2p2 3s2 3p2
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9.2 a) 120 b) If the blue balloon expands‚ the angle between red and green balloons decreases. c) Nonbonding (lone) electron pairs exert greater repulsive forces than bonding pairs‚ resulting in compression of adjacent bond angles. 9.12 a) Both molecules would be symmetrical because all four surrounding atoms are the same. In a symmetrical tetrahedron‚ the four bond angles are equal to each other‚ with values of 109.5°. The H-C-H angles in CH4 and the O-Cl-O angles in ClO4- will have
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