Energetics Questions and Answers

Calculate the amount of heat needed to melt 133. g of solid acetic acid (HCH₂CO₂) and bring it to a temperature of 44.2 °C Be sure your answer has a unit symbol and the correct number of significant digits.

14.0 g of cream at 22.9 °C are added to an insulated cup containing 100.0 g of coffee at 71.4 °C. Calculate the equilibrium temperature of the coffee. You may assume no heat is lost to the cup or surroundings, and that any physical properties of cream and coffee you need are the same as those of water. Be sure your answer has 3 significant digits.

What is the heat capacity of an aluminum cup that weighs 13.80 g? The specific heat of aluminum is 0.897 J/g 'C'. Round to three significant figures. g 'C' Provide your answer below: joules per degree celsius

If 2.300 moles of water react completely, according to the following equation, what is the total change in enthalpy? 6 CO₂ + 6H₂O C6H₁2O6 +60₂ AHrxn=2,803 kJ Report your answer using four significant figures.

The standard heat of formation for NO₂ is 33.2 kJ/mol. How much energy is required to form 590.0 g of NO₂ from its respective elements in kilojoules? Report your answer using three significant figures. Provide your answer below: kJ

J A 1.25 g sample of copper (CCu = 0.386 ) is initially at a temperature of 25.0 °C. If the sample absorbs 87.4 J of heat, what is its final temperature? Report your answer with the correct number of significant figures.

Draw and label the full orbital energy level diagram for a ground-state arsenic atom. Note: On the left-side you will have an arrow indicating energy; to the right of this, you will feature each orbital as a box) (b) (1 pt) Write the condensed electron-configuration of the arsenic atom. (c) (2 pts) List the corresponding number of core and valence electrons.

What is ΔHrxn (in kJ) for the formation of tungsten carbide, W(s) + C(graphite) → WC(s) given: 1.2W(s) + 302(g) → 2WO3(s); ΔHrxn = -1680.6 kJ/mol 2. C(graphite) + O2(g) → CO2(g); ΔHrxn = -405.1 kJ/mol 3. 2WC(s) +502(g) → 2WO3(s) + 2CO2(g); ΔHrxn=-2391.6 kJ/mol

A chemistry student weighs out 0.0645 g of sulfurous acid (H₂SO3), a diprotic acid, into a 250. mL volumetric flask and dilutes to the mark with distilled water. He plans to titrate the acid with 0.1800 M NaOH solution. Calculate the volume of NaOH solution the student will need to add to reach the final equivalence point. Round your answer to 3 significant digits.

A patient arrives in the emergency room with a burn caused by steam. Calculate the heat that is released when 10.7 g of steam at 100. °C hits the skin, condenses, and cools to body temperature of 37.0 °C. (For water, 540 cal (2260 J) is needed to convert 1 g of water to vapor at 100 °C.) Express the heat to three significant figures and include the appropriate units. heat = 0 μà Value Daquest Answer Units ?

A piece of metal weighing 5.1 g at a temperature of 48.6 C was placed in a calorimeter into 20 mL of water at 22.1 °C, and the final equilibrium temperature was found to be 29.2 C. What is specific heat of the metal?

Using the heat of vaporization of benzene, 395 J/g, calculate the grams of benzene that will condense at its boiling point if 7.50 kJ is removed. Express your answer with the appropriate units.

Learning Goal: To calculate the total energy required to convert a solid to a gas using heat capacity, heat of fusion, and heat of vaporization. The amount of heat required to melt one mole of a solid is called the heat of fusion (AHfus). The amount of heat required to vaporize (boil) one mole of a liquid is called the heat of vaporization ( AHvap). The heat of fusion and the heat of vaporization can be used to calculate the amount of heat needed to melt or vaporize, respectively, a given amount of substance. For example, the heat of fusion for H₂O is 6.02 kJ/mol, which means that 6.02 kJ of heat is needed to melt a mole of ice. Twice as much heat is needed to melt twice as much ice, as shown here: 2.00 mol x 6.02 kJ/mol = 12.0 kJ How much heat is required to raise the temperature of 45.0 g of water from its melting point to its boiling point? Express your answer numerically in kilojoules. ▸ View Available Hint(s) 18.8 kJ Submit Previous Answers Correct Correct answer is shown. Your answer 18.9 kJ was either rounded differently or used a different number of significant figures than required for this part. Part C How much heat is required to boil 45.0 g of water at its boiling point? Express your answer numerically in kilojoules. View Available Hint(s)

Part A A patient arrives in the emergency room with a burn caused by steam. Calculate the heat that is released when 10.7 g of steam at 100. °C hits the skin, condenses, and cools to body temperature of 37.0 °C. (For water, 540 cal (2260 J) is needed to convert 1 g of water to vapor at 100 °C.) Express the heat to three significant figures and include the appropriate units.

The heat of fusion of water is 79.9 cal/g, the heat of vaporization of water is 540 cal/g, the specifc heat of ice is 0.492 cal/deg/g, the specific heat of steam is 0.488 cal/deg/g and the specific heat of liquid water is 1.00 cak/deg/g. How much heat would be needed to convert 10.25 g of ice at -15 °C to steam at 121 °C?

For the reaction H₂(g) + O₂(g) → H₂0) Calculate the enthalpy change when 5.88 g of hydrogen gas is reacted with excess oxygen. -48.6 kJ 834 kJ -834 kJ 1.68 × 10³ kJ -1.68 × 10³ kJ

Write the balanced equation for the combustion of 1-naphthol, C₁0H,OH, to give CO₂ and H₂O. Phases are optional. combustion reaction: How many milligrams of CO₂ and H₂O are produced from the complete combustion of 3.575 mg of C₁0H,OH?

How many moles of barium are in a 25.0 g sample of barium? • Your answer should have three significant figures.

What amount of heat (in kJ) is required to convert 14.4 g of an unknown liquid (MM = 67.44 g/mol) at 43.5 °C to a gas at 128.2 °C? (specific heat capacity of liquid = 1.18 J/g °C; specific heat capacity of gas = 0.792 J/g °C; ΔHvap = 30.1 kJ/mol; normal boiling point, Tb = 97.4°C)

A photon of blue light has a frequency of 7.50 × 1014 Hz. Calculate the wavelength of this photon (c = 3.00 × 108 m/s) in nanometers.

Part C How many kilojoules are released when 299 g of O2 is produced? Express your answer with the appropriate units.

At the end of 2012, global population was about 7.0 billion people. What mass of glucose in kg would be needed to provide 1800 cal/person/day of nourishment to the global population for one year? Assume that glucose is metabolized entirely to CO₂ (g) and H₂O(1) according to the following thermochemical equation: C6H12O6 (8) + 602 (g) 6 CO2(g) + 6H₂O(1) AH = -2803 kJ

How many kilojoules are released when 2.50 mol of H₂O2 reacts? Express your answer with the appropriate units. How many kilojoules are released when 299 g of O₂ is produced? Express your answer with the appropriate units.

Consider the following reaction: 2Mg(s) + O2(g) → 2MgO(s), AH = -1204 kJ Calculate the amount of heat transferred when 3.51 g of Mg(s) reacts at constant pressure. Express your answer in kilojoules to three significant figures. AH = How many grams of MgO are produced during an enthalpy change of -237 kJ ? Express your answer in grams to three significant figures.

11. If 25.0 g of AgNO3 are reacted with excess Na3PO4, what is the percent yield of Ag3PO4 if 18.7 g of Ag3PO4 was produced? ang cM to aslom 82.8 ni bnuot amsip to edmun srit afsluols a

A car engine uses the combustion of fuel to move a system of gears that move its wheels. Not all of the fuel's energy is transferred to the wheels. Which two options describe what happens to the rest of the energy? A. Some energy is lost because of the heat produced by the engine. B. Some energy is lost because of the weight of the car. C. Some energy is lost because of friction in the car's moving parts. D. Some energy is lost because it is transformed into chemical energy. E. Some energy is lost because it is transformed into potential energy.

A person uses 441,2 kcal of energy to run a race. Convert the energy used for the race to the following energy units: (provide an answer in 4 significant figures) I Calories calories Food Calories Joules Kilojoules

Why is the lattice energy of LiF expected to be greater than the lattice energy than NaF? The lithium ion is smaller than the sodium ion The lithium ion is larger than the sodium ion. The lithium ion has a smaller charge than the sodium ion. The lithium ion has a larger charge than the sodium ion.

Is each of the following steps for the formation of magnesium chloride endo- or exothermic? Vaporization of magnesium Ionization of magnesium Dissociation of chlorine Chlorine gaining electrons to form the chloride ion Magnesium and chloride ions combining to form the solid salt

Suppose a certain material has a specific heat of 0.863 J/g C. If 9.89 kJ of heat is applied to 444.9 g of the material at 21.4°C, what is the final temperature (in "C) of the material?

When 8.73 g of hydrocarbon (molar mas = 328.5 g/mol) is burned in a bomb calorimeter, the calorimeter increases in temperature by 2.00°C. If the heat capacity of the bomb calorimeter is 1.260 kJ/°C, what is the heat of combustion for the hydrocarbon, in kJ/mol?

If a process can be written as the sum of several stepwise processes, the enthalpy change of the total process equals the product of the enthalpy changes of the various steps. True False

The dissolution of ammonium nitrate in water results in a decrease in temperature of the water. NH4NO3(s) + H₂O(l) → NH4+ (aq) + NO3-(aq) Which statement about this reaction is true? ΔHxn < 0, reaction is exothermic ΔHxn > 0, reaction is exothermic ΔHrxn > 0, reaction is endothermic ΔHrxn <0, reaction is endothermic ΔHrxn = 0, because energy cannot be created or destroyed

How much heat is gained by cobalt when 28.7 g of cobalt is warmed from 27.5°C to 71.9°C? The specific heat of cobalt is 0.421 J/(g. °C). 8.69 10² J 30.27 J 5.36 10² J 18.69 J 3.32 10² J

45 grams of an unknown substance undergoes a temperature increase of 38 °C after absorbing 4172.4 Joules. What is the specific heat of the substance? 240 J/g°C 2.44 J/g°C 24.4 J/g°C 4.18 J/g°C

A student mixes 67.0 mL of a 2.01 M sodium hydroxide solution with 23.1 mL of 6.45 M hydrochloric acid. The temperature of the mixture rises 23.5°C. The density of the resulting solution is 1.00 g/ml and has a specific heat capacity of 4.184 J/ g °C. The heat capacity of the calorimeter is 16.97 J/ °C. Part 1: (a) Identify the limiting reagent for the reaction. NaOH Part 2 out of 3 : (b) Calculate the heat of reaction (in J). qrxn = *10 J Enter your answer in scientific notation.

A sample of calcium carbonate [CaCO3 (s)] absorbs 45.5 J of heat, upon which the temperature of the sample increases from 21.1°C to 28.5°C. If the specific heat of calcium carbonate is 0.82 J/g-K, what is the mass (in grams) of the sample?

A 22.4 g piece of an unknown metal loses 672 J of energy when it cools from 95.3°C to 28.5°C. Type numbers in the boxes. What is the specific heat of the metal, in J/(g°C)? J/(g°C)

For the Bohr model, a) what is the absolute energy that corresponds to an electron transition from n = 5 to n =2? b) Is the change in energy positive or negative?

(a) Write the balanced chemical equation that represents the standard heat of formation of Cl(g) at 298 K. Be sure to specify states. Write fractions with a slash, such as 1/2 for one half. If a box is not needed leave it blank. (b) The standard enthalpy change for the following reaction is 804 kJ at 298 K.

Calculate the change in enthalpy for the following reaction: 2 NH3(g) + 4H₂O(l)→ 2 NO2(g) + 7 H2(g) Given: N2(g) + 3 H2(g) → 2 NH3(g) ΔH-207.0 kJ N2(g) + 2O2(g) → 2 NO2(g) ΔH = -148.5 kJ H2(g) + 1/2O2(g) → H₂O(l) ΔH = +78.7 kJ a) +434.2 kJ b) -256.3 kJ c) +40.7 kJ d) -208.4 kJ

Ethyne gas may react with hydrogen gas to form ethane gas in the following reaction: C₂H₂(g) + 2 H₂(g) → C₂H6(g) Predict the standard enthalpy change for the reaction of 200 g of ethyne, using the following information. After using Hess' law, refer back to Sample Problem 11.2 on page 491. (1) C₂H₂(g) + 5/2O₂(g) → 2 CO₂(g) + H₂O(l) Δ1H=-1299 kJ Δ₂H = -286 kJ (2) H₂(g) + 1/2O₂(g) → H₂O(l) (3) C₂H6(g) + 7/2 O₂(g) → 2 CO₂(g) + 3 H₂O(l) Δ1H=-1560 kJ

Without doing any calculations, match the following thermodynamic properties with their appropriate numerical sign for the following endothermic reaction. 2N2(g) + O₂(g) 2N₂O(g)

When H₂(g) reacts with O₂(g) according to the following reaction, 59.02 kcal of energy are evolved for each mole of H₂(g) that reacts. Complete the following thermochemical equation. 2H₂(g) + O₂(g) →→→ 2H₂O(g) ΔH = kcal

Using the following data, calculate the standard enthalpy of reaction for the coal gasification process. 2C(s) + 2H₂O(g) Ⓡ CH4(g) + CO₂(g). C(s) + H₂O(g) Ⓡ CO(g) + H₂(g); DH° = +131.3 kJ CO(g) + H₂O(g) Ⓡ CO₂(g) + H₂(g); DH° = -41.2 kJ CO(g) + 3H₂(g) Ⓡ CH4(g) + H₂O(g); DH° = -206.1 kJ -116.0 kJ -378.6 kJ 378.6 kJ +15.3 kJ -157.2 kJ

Write the balanced chemical equation that represents the standard heat of formation of NaCl(g) at 298 K. Be sure to specify states. Write fractions with a slash, such as 1/2 for one half. If a box is not needed leave it blank. (b) The standard enthalpy change for the following reaction is -50.6 kJ at 298 K. N₂H4(1) N₂(g) + 2 H₂(g) What is the standard heat of formation of N₂H4(I)?

Given the molar enthalpy of combustion of propanol (C3H7OH) is -2021 kJ/mol, how much heat (in kilojoules) will be released by the combustion of 9.5 g at standard pressure? a) -320 kJ b) -5122.9 kJ c) 1.95 kJ d) 2422.5 kJ

Which of the following is the correct value for the heat needed to convert one mole of carbon tetrachloride (CC14) from a liquid to a gas? Given: Standard Enthalpy of Formation for CCl4(0 is -139.5 kJ/mol Standard Enthalpy of Formation of CCl4(g) is -103.2 kJ/mol a) +103.2 kJ/mol b) -36.3 c) +36.3 kJ/mol d) -242.7 kJ/mol

A catalyst changes the reaction rate by lowering the: a) equilibrium constant of the reaction b) All of these options are correct. c) enthalpy of the reaction d) activation energy of the reaction

Given the molar enthalpy of combustion of ethanol (C₂H5OH) is -1368.54 kJ/mol, how much heat (in kilojoules) will be released by the combustion of 6.5 g at standard pressure? a) 29.7 kJ b) 193.1 kJ c) 1805.1 kJ d) 8892 kJ