Answering at least a question in SOCRATIC has been a new habit I recently developed. The subjects are basically divided into three main groups: Science, Math and Humanities. The dedication shown by the community is just amazing, so much effort put in when answering the questions posted. It’s really too bad that SOCRATIC decided to close the website to contribution effective from Aug 15, 2018. That’s why I decided to log the questions I have answered here.   CHEMISTRY

• Measurement
  • SI System of Measurement
    • What is the SI unit of mass?
  • Scientific notation
    • What is 0.0015kg in scientific notation?
    • How do you write 8,670,000,000 in scientific notation?
  • Unit conversions
    • How do unit conversions work?
    • How many pints and ounces is 59 fl oz?
  •  Density
    • Why does ice have a different density than liquid water?
    • The density of ether is 0.714 g/mL. what is the mass of 1.45 L of ether?
  • Temperature
    • What is 350 Kelvin on the Celsius scale of temperature?
• Matter
  • Classification of matter
    • Is salt and pepper a heterogeneous mixture?
• Ionic Bonds
  • Formula
    • What would be the correct formula of the ionic compound formed if a certain metal M with valence electron configuration Ns2 reacted with a nonmetal valence electron Ns2 Np4?
    • Please,why is MnO2-4 i.e manganese(vi)oxide not MnO3?…i still dont get it..i mean if u calculate the oxidation number with the latter it’ll still be +6
    • How do polyatomic ions differ from monatomic ions?
• The Mole Concept
  • Atomic mass
    • How do you calculate the relative formula mass (M) of calcium carbonate? Relative atomic masses C = 12, O = 16, Ca = 40?
  •  Mole
    • How many moles of $S$ are in 25 g of $S$?
    • How many atoms of each element of $AgN{O}_3$ are in 0.15 mol of $AgN{O}_3$?
    • How many $M{g}^{2+}$ ions are present in 3.00 moles of $MgC{l}_2$?
  • Empirical and molecular formulas
    • What is the empirical formula for C3H6O3?
    • Benzene and acetylene have the same empirical formula, CH. However, benzene has a molar mass of 78 g, and acetylene has a molar mass of 26 g, what are the molecular formulas of benzene and acetylene?
  • Percent composition
    • Calculate the percentage of water of hydration in barium chloride crystals (the atomic weight of Ba is about 137.4 g/mol)?
• Periodic Table
  • Metals and nonmetals
    • What are the physical characteristics of nonmetals?
• Intermolecular Bonding
  • Polarity of bonds
    • How can I determine bond polarity?
• Electron Configuration
  • Electron configuration
    • What is the electron configuration of chlorine?
    • Can somebody explain me what are the vacant 3d orbitals of silicon? Silicon configuration is 1s2 2s2 2p6 3s2 3p2 Where are the d orbitals?
• Chemical Reactions
  • Reviews of elements and compounds
    • What is the compound formula for arsenic monophosphide?
  • Balancing chemical equations
    • $U{O}_3$ reacts with $H^{+}$ ions to produce $U{O}_2^{2+}$ ions and water. Write the balanced equation for this reaction?
    • How do you solve $K_{2}PtC{l}_4+N{H}_3\to Pt{\left(N{}_3\right)}_{2}C{l}_2+KCl$?
  • Double replacement reactions
    • How do you balance double replacement reactions?
    • Chemical reaction takes place when iron dust is added into copper sulphate solution but no reaction takes place when copper dust is added into ferrous sulphate solution, why?
• Stoichiometry
  • Equation stoichiometry
    •  How do you balance C 2 H 5 O H ( l ) + O 2 ( g ) → C O 2 ( g ) + H 2 O ( g ) and determine the mass of C O 2 produced from the combustion of 100.0 g ethanol?
    • How many grams of hydrogen are necessary to react completely with 2.3 moles of nitrogen, in the reaction N2+3H2 = 2NH3?
    • Calculate the weight of iron at which will be converted into its oxide by action of 18 gram of steam Fe+H2O —-heat——->Fe3O4+H2?
•  Gases
  • Gay Lusaac’s law
    • The temperature of 200.0 mL of a gas originally at STP is changed to -25C at constant volume. Calculate the pressure of the gas in atm?
  • Charles’ law
    • A flexible .556 L container holds air at a temperature of 27.3 degrees C. If the container is cooled so that the new volume of the gas is .214 L, what is the new temperature of the air in Celsius?
  • Combined gas law
    • 250 ml of oxygen gas is collected over water at a pressure of 1.27 atm and a temperature of 16 degrees C. What volume of dry gas will there be at 105 kpa and -22 degrees C?
  • Ideal gas law
    • If 20.0 g of $N_2$ gas has a volume of 0.40 L and a pressure of 6.0 atm, what is its Kelvin temperature?
  • Dalton’s partial pressure
    • A mixture of Nitrogen, Oxygen, and Helium gas is collected in a container at 1 atmosphere, if the partial pressure of oxygen is 320 mm and helium’s pressure is 112, what is the partial pressure of the nitrogen?
• Solutions
  • Measuring concentration
    • %(m/m)
      • What is the percent by mass of the solute of a solution made by dissolving 29 grams of sodium lithium chloride in water which has a density of the solution of 1.00 grams/ml, to a final volume of 202 ml solution?
      • What is the mass percent of salt in a solution that made by dissolving 10g salt in 60g H2o?
      • How many grams of NaCl are needed to prepare 35 kg of a 5 % (m/m) solution?
      • Calculate the concentration (% m/m) of a solution that contains 27.5 g of NaOH dissolved in 200 g of water?
    • %(v/v)
      • Determine the amount of water required to produce 500 ml of a solution that is 35% of alcohol dissolved in water?
    • Molarity
      • Determine the molarity of a 4.5 L solution that contains 100g of NaOH dissolved (Na=23 g/mol, O=16 g/mol, H=1 g/mol)?
    • Dilution
      • A stock solution of hydrochloric acid with 1.25 M, 25 mL was diluted to 75 mL with water. What was the new concentration of this diluted acid?
      • A stock solution contains 5 g per 100 ml of sucrose. How many ml of this stock solution would you use to prepare 1 litre of sucrose solution at a concentration of 0.25 g per litre?
• Acids and Bases
  • Acid and Bases Theories
    • How did Arrhenius describe acids?
    • What is the difference between Arrhenius, Bronsted-Lowry, and Lewis acids and bases?
  • Conjugate acid and base
    • What is a conjugate acid and base pair?
  • Ionization constant
    • What does the ionization constant of an acid or a base indicate about either the acid or the base?
    • What is the equation for the base ionization constant of RbOH?
    • What is the equation for the acid ionization constant of HNO3?
  • Calculations
    • What is the [OH-] in a solution that has a [H3O+] = 2.0 x 10-2 M?
• Organic Chemistry
  • Hydrocarbons
    • For the first 6 member in the series of Alkenes plot the Number of the hydrogen atom and on the other axis use this graph to derive the formula of the alkenes that has 10 carbon atoms?
  •  Biomolecules
    • What is the structural formula for lysine with pH of 4?
  • Polymer Chemistry
    • What is the name for a reaction that links monomers to form a chain?
  • Aromatic Compound
    • Show all the steps to how 3-chloroaniline can synthesis from benzene ?
  • Bonding
    • When a carbon atom has $s{p}^3$ hybridization, what type of bonds does it have?
    • What is the hybridization of the sulfur atom in SO2?

ORGANIC CHEMISTRY

• Ways to represent molecule
  • What is the difference between expanded and condensed structural formulas?
• Hybridization and Atomic and Molecular Orbitals
  • What are sp, sp2, sp3 orbitals?
  • What is an sp2 hybridized carbon atom?
• Functional Groups
  • Which statement is true for the following molecule?
• IUPAC
  • What is the IUPAC name of the following compound?

  ALGEBRA

• Reese brought 2 sandwiches for her school lunch. Each sandwich was cut into fourths. After she ate lunch, Reese had 3 pieces of sandwich left. How many pieces did Reese eat?
• How do you solve this system of equations: $2x+y=-2\text{and}5x+3y=-8$?
• Sarah has made 21 bracelets to sell at craft fair. If this is 70% of the bracelets she wants to make, how many more bracelets does she need to make?
• Jillian works 2 jobs. She earns $8.25 her first. She earns $10.15 at her second. If Jillian earned a total of $387 by working $x$ hours at her first job and $y$hours at her second job, how do you write an equation that represents this situation?
• How do you find the values of x given $4\times 27+3\times 34-94=x$?
• If y=kx, where k is a constant, and y=24 when x=6, what is the value of y when x=5?
• What is the luggage fuel cost in Canadian dollars for each airline if all passengers bring the maximum luggage (see picture for details)?
• Ms. Koblin commutes 1.5 hours per day to work. If Ms. Koblin spent 28.5 hours commuting, how many days was she driving to work last month?
• How do you factor by grouping $7-2x^5-3+2+12$?
• How do you evaluate $-5--4\frac{1}{4}+3\frac{1}{4}+-6$?
• If one copy of a new book by Amanda’s favorite author cost $9.45. If a total of 2,740 copies of the book were sold on the first day of the books of the book’s release, what were the total sales that day?
• For her birthday party, Melonie wants to make a punch drink made with 2 1/2 gallons orange juice, 4 quarts cranberry juice, and 3 quarts apple juice. How much punch will she make?
• Latanya made a 17-minute phone call from her hotel in France and was charged 17 euro. At the time, $1 was worth 0.82 euro. Find the cost per minute of the call in dollars?
• Maggie is rock climbing. After reaching the summit, she descends 14 feet in 213 minutes. If she continues at this rate, where will Maggie be in relation to the summit after 8 minutes?