This chemistry question involves key chemical concepts and calculations. The detailed solution below walks through each step, from identifying the reaction type to computing the final answer.
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Here are the answers to your questions: 8. One use of graphite is as a lubricant (due to its layered structure allowing layers to slide past each other easily). It is also used in pencils and as electrodes. 9. To convert 25^ to Kelvin: Temperature in Kelvin = Temperature in Celsius + 273.15 Temperature in Kelvin = 25 + 273.15 Temperature in Kelvin = 298.15 K The temperature is 298.15 K. 10. Noble gases are unreactive because they have a full outer electron shell (a stable octet, or duet for helium). This electron configuration makes them very stable and they have no tendency to gain, lose, or share electrons. 11. To calculate the molar mass of CaCO_3: Given atomic masses: Ca=40, C=12, O=16. Molar mass of CaCO_3 = (1 × Ca) + (1 × C) + (3 × O) Molar mass of CaCO_3 = (1 × 40) + (1 × 12) + (3 × 16) Molar mass of CaCO_3 = 40 + 12 + 48 Molar mass of CaCO_3 = 100 g/mol The molar mass of CaCO_3 is 100 g/mol. 12. Atomic radius is defined as the distance from the center of the nucleus to the outermost electron shell of an atom. 13. One property of an ionic compound is that it typically has a high melting point. (Other properties include high boiling points, being soluble in polar solvents like water, and conducting electricity when molten or dissolved in water). 14. Molar mass is defined as the mass of one mole of a substance. It is expressed in grams per mole (g/mol). 15. The periodic table has 18 groups. 16. Charles's Law states that for a fixed mass of gas at constant pressure, the volume of the gas is directly proportional to its absolute temperature. Mathematically, this can be expressed as (V_1)/(T_1) = (V_2)/(T_2). 18. To calculate the volume of the gas at 250 kPa, we use Boyle's Law, which states that for a fixed mass of gas at constant temperature, the pressure is inversely proportional to its volume (P_1V_1 = P_2V_2). Step 1: Identify the given values. Initial volume (V_1) = 2.5 L Initial pressure (P_1) = 100 kPa Final pressure (P_2) = 250 kPa Final volume (V_2) = ? Step 2: Apply Boyle's Law formula. P_1V_1 = P_2V_2 Step 3: Rearrange the formula to solve for V_2. V_2 = (P_1V_1)/(P_2) Step 4: Substitute the values and calculate. V_2 = 100 kPa × 2.5 L250 kPa V_2 = 250 kPa · L250 kPa V_2 = 1 L The volume of the gas at 250 kPa is 1 L. 19. To calculate the number of molecules in 3 moles of a substance (assuming "oxygen gas CO_2" refers to 3 moles of molecules, despite the contradictory chemical formula): Step 1: Identify the given values. Number of moles = 3 mol Avogadro's number = 6.02 × 10^23 molecules/mol Step 2: Calculate the number of molecules. Number of molecules = Number of moles × Avogadro's number Number of molecules = 3 mol × (6.02 × 10^23 molecules/mol) Number of molecules = 18.06 × 10^23 molecules Number of molecules = 1.806 × 10^24 molecules The number of molecules is 1.806 × 10^24 molecules. 3 done, 2 left today. You're making progress.