General Questions and Answers

Which trends appear as the elements in Period 3 are considered from left to right? 1. Metallic character decreases, and electro- negativity decreases. 2. Metallic character decreases, and electro- negativity increases. 3. Metallic character increases, and electro-negativity decreases. 4. Metallic character increases, and electro-negativity increases.

At -5, 4.0 g of an unknown gas occupies a volume of 1.8 L at a pressure of 1.5 atm. a) Calculate the molar mass of the gas. b) Determine the likely identity of the gas out of the following set: N₂, O₂,CO₂

Which group on the periodic table contains the neutral atom with the following electron configuration? 1s² 2s² 2p³ Group 2 Group 3 Group 7 Group 15

Which option includes only the chemical properties of carbon? It is flammable and reacts with oxygen. It is malleable and is toxic when consumed. It has a density of 2.25 g/mL and high specific heat. It has a melting point of 3550°C and a boiling point of 4827°C.

Given the following equation: 2 K₂O₂(s) + 2 H2O(l) --> O₂(g) + 4 KOH(aq) How many grams of H₂0 are needed to produce 0.5 moles of KOH? (molar mass of H₂0 = 18.0 g/mole) 0.5 grams 4.5 grams 9 grams 18 grams

Which formula represents iron (III) chloride? Fecl FeCl₃ Fe₃CI Fe₃Cl₃

The pressure of 45 L of gas is changed from 900 mm Hg to 300 mm Hg. What is the new volume? 135 L 22.5 L 165 L 15.0 L

The mass ratio of sodium to fluorine in sodium fluoride is 1.21:1. A sample of sodium fluoride produced 23.4 g of sodium upon decomposition. How much fluorine (in grams) was formed? Express your answer to three significant figures.

When limestone (solid CaCO3) is heated, it decomposes into lime (solid CaO) and carbon dioxide gas. This is an extremely useful industrial process of great antiquity, because powdered lime mixed with water is the basis for mortar and concrete - the lime absorbs CO₂ from the air and turns back into hard, durable limestone. Suppose some calcium carbonate is sealed into a limekiln of volume 500. L and heated to 520.0 °C. When the amount of CaCO3 has stopped changing, it is found that 3.84 kg have disappeared. Calculate the pressure equilibrium constant Kp, this experiment suggests for the equilibrium between CaCO3 and CaO at 520.0 °C. Round your answer to 2 significant digits. Note for advanced students: it's possible there was some error in this experiment, and the value it suggests for Kp, does not match the accepted value. Kp =

An atom has the atomic number of 48. a. What element is this? b. What family of elements is this element in? c. How many protons does it have? d. How many electrons does it have? e. If the total mass is 96 amu, how many neutrons does this isotope of the element have? f. When becoming an ion, will this element gain or lose electrons? g. How many electrons will it gain or lose?

The following Lewis diagram represents the valence electron configuration of a main-group element. .X. This element is in group According to the octet rule, this element would be expected to form a(n) with a charge of If X is in period 4, the ion formed has the same electron configuration as the noble gas The symbol for the ion is

B. (05.06 MC) During an experiment, the percent yield of calcium chloride from a reaction was 85.22%. Theoretically, the expected amount should have been 113 grams. What was the actual yield from this reaction? CaCO3 + HCl → CaCl₂ + CO₂ + H₂O (5 points) 99.0 grams 113 grams 121 grams 96.3 grams

7b. One of the waste products produced by kidneys is creatinine. A healthy range of creatinine in human blood is between 0.50 mg/dL and 1.1 mg/dL. Elevated levels of this compound could indicate a problem with kidney function. The concentration of creatinine in patient's blood was reported in g/L: 0.0082 g/L. Is this value within the normal range? If it is not, is this concentration low or high? Confirm your answer with your calculations and show all the work. The concentration of creatinine =_mg/dL. It is the normal range.

When 236 g of copper (Cu) reacts with 32 g of oxygen gas (O₂) to form copper (II) oxide, no copper or oxygen is left over. How much copper (II) oxide (CuO) is produced? 2Cu + O₂ → 2CuO 236g + 32g → ?

A redox reaction involves the reduction of one substance (gaining electron(s)) and the oxidation (losing electron(s)) of another. Examples of reduction and oxidation are shown. Combine the two given reactions like algebraic equations and write the net, or overall, redox equation.

A propane tank inspector detected rust in a tank. The empty cylinder valve was not closed, and water vapor settled inside causing rust to form. The cylinder is unusable. Select the combination reaction for the formation of rust. A. Fe₂O3 → 2Fe + O₂ B. 4Fe + 3O₂ → 2Fe₂O3 C. FeCl₂ + H₂O → FeO + 2HCI D. Fe₂O3 + 3CO→ 2Fe + 3CO₂

A 3.24-gram sample of NaHCO3 was completely decomposed in an experiment. 2NaHCO3 - Na₂CO3 + H₂CO3 In this experiment, carbon dioxide and water vapors combine to form H₂CO3. After decomposition, the Na₂CO3 had a mass of 2.19 grams. A. Determine the mass of the H₂CO3 produced. B. Calculate the percentage yield of H₂CO3 for the reaction. Show your work or describe the calculation process in detail.

An order is given to administer methylprednisolone, an anti-inflammatory drug, by IV at a rate of 36 mg every 30. min. The IV bag contains 125 mg of methylprednisolone in every 2.0 mL. What should the flow rate be in milliliters per minute (mL/min)?

The compound silver acetate is a strong electrolyte. Write the reaction when solid silver acetate is put into water:

Describe the scale used to measure the basicity of a substance. Demonstrate how you could differentiate a weak base from a strong one.

Two students are conducting an experiment for a lesson on solubility and intermolecular forces. They first weigh 50 g of table salt in a beaker. Then, they measure 250 mL of water in a graduated cylinder and add it to the beaker containing the 50 g of salt. They notice that the salt dissolves in the water very easily. Next, they proceed to add another 50 g of salt. After stirring for a while, they notice not all the salt has dissolved. 9. When NaCl is added to water the strength of intermolecular forces between water molecules and a substance's ions in solution affect the solubility in what way? A. The molecules dissociate into Na and Cl protons which are then surrounded by a shell of water molecules called a closed shell. B. The molecules dissociate into Na and Cl ions which are then surrounded by a shell of water molecules called a solvation shell. C. The molecules dissociate into Na and Cl photons which are then surrounded by a shell of water molecules called a valence shell. D. The molecules dissociate into Na and Cl neutrons which are then surrounded by a shell of water molecules called an electron shell.

The policy that requires most employers to take positive steps to remedy the effects of past discriminations is called anti-discrimination policy equal opportunity employment policy affirmative action positive employers policy

For the reaction SO3 + H₂O → H₂SO4 how many grams of sulfuric acid, H₂SO4, can be produced from 160 g of sulfur trioxide, SO3, and an excess of water? 98 grams 1.2 x 1024 grams 196 grams 2 grams

A chemist has 315 g of iron (III) phosphate, FePO4. How many representative particles are present in the sample? Hint: You'll need the molar mass of FePO4 1 mole = 6.02 x 1023 representative particles 1.62 x 1024 molecules 2.05 x 1024 molecules 0.98 x 1024 molecules 1.26 x 1024 molecules

What is surface tension? Describe how surface tension in water is useful for plants and animals.

Antoine works for a big international bank. His job requires that he flies from Los Angeles to New York City twice a month. Whether at home or on business, Antoine tries to eat locally grown food since it does not need to travel a long distance (using big fossil fuel burning trucks to get it to him from far away). He also prefers to put a sweatshirt on at home rather than turning on the heater. He is constantly on his phone for work and leaves his phone charger plugged in all the time so his phone is easy to charge. Which of the following is INCREASING Antoine's carbon footprint? MARK ALL THAT APPLY. putting the heater on too high leaving his phone charger plugged in all the time flying a very long distance twice a month (he should do some Zoom meetings instead!) eating too much food

Which statement about gases is true? They are made up of particles that always move very slowly. They are made up of particles that travel in a curved path when in motion. They are made up of hard spheres that vibrate quickly in stationary positions. They are made up of hard spheres that are in random motion.

Calculate the molarity of sodium chloride in a half-normal saline solution (0.45% NaCl). The molar mass of NaCl is 58.44 g/mol.

A student measured the mass of a block of metal four times. She got the following measurements; 21.8 g, 22.00 g, 22.1 g, and 21.9g. The metal actually weighed 22.0g. Describe these values in terms of accuracy and precision. Calculate the percent error in the above problem using 21.9 g.

Propane is a hydrocarbon that needs an abundant amount of oxygen to burn and yields carbon dioxide and water, as shown in the equation. When propane is burned, a chemical reaction occurs, and all the atoms and molecules are rearranged in the end product. Energy is needed to break the methane and oxygen bonds. Once all the bonds have been broken, new bonds are formed in the end product of carbon dioxide and water, releasing heat and energy. C3H8 +5O2 3CO₂ + 4H₂O What is this type of reaction called? A. synthesis reaction B. combustion reaction C. combination reaction D. double replacement reaction

2. Balance the following chemical equations. Write the sequences to the right. 1. CaCO3 → CaO + CO₂ 2. Al + H₂SO4 → Al₂(SO4)3 + H₂ 3. C6H6 + O₂ → CO₂ + H₂O C=12, H=12, O=30 4. BaO2 → BaO + O₂ 5. AgNO3 + CuCl2 -> AgCl + Cu(NO3)2

Use the balanced equation below to answer the associated questions. Show work (no work, half credit) 2NaOH(aq)+MgCl2(aq)-2NaCl(aq)+Mg(OH)2(s) Molar mass of NaOH Molar mass of MgCl2 Molar mass of NaCl Molar mass of Mg(OH)2

2 Al + 3 CuSO4 → 3 Cu + 1 Al2(SO4)3 Suppose during a science experiment, 1.75-g of aluminum metal reacts with 1.50-g of copper(II) sulfate. a. How much solid copper should theoretically form? Hint: You'll need the molar mass of Aluminum, Al, and Copper, Cu. 0.665 g of Cu 0.623 g of Cu 0.498 g of Cu 0.597 g of Cu

A 10 M concentrated stock solution of NaCl was used to prepare 5 liters of diluted 1 M solution. Which of the following statements is true about the process used to achieve this required dilution? (5 points) The volume of stock solution used was more than 5 liters. The volume of stock solution used was less than 0.4 liters. The volume of the solvent used was less than 0.4 liters. The volume of the solvent used was less than 5 liters.

4. Use the following balanced equation to carry out the mole to mole questions 2C₂H₂ + 5O₂ 4CO₂ + 2 H₂O a) If I have 20 mole of C₂H₂ how many mole of CO₂ will be yielded? b) If I have 0.5mol of C₂H₂ how many mole of O₂ will be needed? c) If 0.094 mol of H₂O is produced in the above reaction, how many mole of 0, was used to make it?

It is important to always minimize the amount of solvent used, allowing for evaporation. If we add a relatively large excess, we expect our recrystallization to produce lower percent recoveries. A common mistake is to misplace the decimal, resulting in addition of 11x the solvent instead of the recommended 1.1x. If a substance dissolves in a solvent at 1g/464 mL at room temperature and at 1g/15 mL at the solvent's boiling point, what would be the maximum expected amount recovered if using 11x the minimum amount of solvent in recrystallizing 10 g of the substance? Report your answer in grams to one decimal place.

A pile of leaves is lit on fire, and then covered completely with a fire blanket so that the fire goes out. Identify the limiting reactant in this situation a) the fire b) the leaves c) oxygen d) the blanket

4 AIF₁+30₂---> 2 Al₂O3 + 6 F2 1. How many moles of fluorine (F₂) will be produced if there are 20.0 moles of aluminum fluoride (AIF3)? 2. How many liters of F₂ gas will be produced from 2.1 X 10^24 formula units of AIF3?

3. State whether each of the following equations represents a synthesis (s), decomposition(d), single replacement (sr), double replacement (dr), combustion (c) or an acid-base (ab) reaction. 1. CO₂ --->C + 0₂ 2. NaCl + AgNO3 → NaNO3 + AgCl 3. S + Cl₂ → SC1₂ 4. BaCl₂ + 2NaOH--->2NaCl + Ba(OH)₂ 5. 2C₂H₂ + 50₂---> 4CO₂+ 2 H₂O 6. Zn + CuSO4 → ZnSO4 + Cu 7. HCI + NaOH ---> H₂O + NaCl 8. Pb(NO3)2 + Mg --->Pb + Mg(NO3)2

If your end product is 1.5 moles of KMnO4, how many moles of manganese oxide were used in the reaction? The equation for the production of potassium permanganate is as follows: 2 MnO₂ + 4 KOH + O₂-2 KMnO4 + 2 KOH + H₂ You must show all work to receive full credit.

What is the volume (in liters) of a 5.82 gram sample of O₂ at STP? Round to 2 decimal places (hundredths).

2NH3(g) + 37 kJ of heat → N₂(g) +3H2(g) Which of the following stressors will cause the equilibrium of this reaction to shift to the left? (Choose all that apply) a. Increase in reactant b. Decrease in reactant c. Increase in product d. Decrease in product Increase in temperature 1. Decrease In temperature

A blacksmith is in the process of making iron horse shoes. Each shoe, mass of 255.15g, is heated to a bright red (816°C), hammered into shape, and then dropped into water to cool. If the bucket contains 4L of water (4000g) initally at room temperature (23°C) what will the final temperature of the iron be? Specific heat of cast iron: 0.461 J/gºC Specifc heat of water. 4.18 J/gºC Show all of your work.

Which ONE of the following statements accurately describes the standard free energy change of a reaction? The amount of heat released when a reaction reaches equilibrium with 1M substrates and products. The amount of work that can be done when a reaction of 1M of substrates and 1M of products reaches equilibrium at pH 7.0 and 298K. The change in cellular energy that determines if a reaction will proceed in the forward direction. The minimum amount of energy that is required for a reaction to proceed in the forward direction.

Coffees and colas are identified as to whether they contain the stimulant caffeine. The percent composition of caffeine is 49.5% C, 5.20% H, 16.5% O, and 28.9% N. What is the molecular formula of caffeine if its molar mass is 194.1 g/mol?

What is the molality of a solution of water and KCl if 50g of KCl were added to 900g of water?

Scientist A produces 83.67 g KMnO4 while Scientist B produces 81.35 g KMnO4. What is the percent yield for Scientist A? What is the percent yield for Scientist B? You must show all work to receive full credit. The equation for the production of potassium permanganate is as follows: 2 MnO₂ + 4 KOH + O₂ - 2 KMnO4 + 2 KOH + H₂

Show the net ionic equation for: 3CuCl₂(aq)+2K,PO₂(aq)→6KCl(aq)+Cu3(PO4)₂(s) Your breakout must include all correct charges and mole numbers. There will be two equations written excluding the starting equation:

When 189.6 g of ethylene (C2H4) burns in oxygen (02) to produce carbon dioxide and water, how many grams of CO₂ are formed? 2 C₂H4 +60O2 ---- 4 H₂O + 4CO2 594.9 g 148.7 g 297.5 g 6.76 g

How many atoms are in 1 mole of Carbon atoms? a) 1.806 x 1024 atoms b) 3 atoms c) 4 atoms d) 6.02 x 1023 atoms