General Chemistry
Improve your experience by picking them
A bus traveling north has a kinetic energy of 2.8 × 106 J. If half of the kinetic energy is converted into heat, how much heat in calories are released and how many grams of water could be heated by this converted energy from 25°C to 45°C? (Specific heat capacity of water is 4.184 J/g°C)
Differentiate molar heat capacity from specific heat capacity.
A 15.0 g mixture of LiCl and KNO3 are dissolved in 150.0 g of water, causing the temperature to increase by 1.68 ºC. Using the heats of dissolution of each component, calculate the mass of each component of the mixture. Use the specific heat of water for the solution.
A 0.55 m aqueous solution of NaI is prepared at 25 ºC. Determine the final temperature of the solution, given that the specific heat capacity of the solution is the same as water and ΔHºsoln of NaI is –7.53 kJ/mol.
Gravitational potential energy is converted to thermal energy due to the vibrations at the point of impact with a surface. It is given by the formula PE = mgh, where m = mass, g = acceleration due to gravity (9.8 m/s2), and h = height. In an experiment, a 2.5 kg aluminum sphere is dropped from a height of 654 m to the ground. Assuming that all of the potential energy is converted to thermal energy, calculate the change in temperature of the aluminum sphere (c = 0.897 J/g ºC).
Determine the energy needed to heat 400 mL of coffee from 30.0 ºC to 90.0 ºC. Use the density and specific heat of water.
A 10.0 g sample of AgNO3 is dissolved with 200.0 g of water in a coffee cup calorimeter at 25.0 ºC. After dissolution, the temperature of the solution dropped to 23.5 ºC. Calculate the ΔH per mole of AgNO3. Use the specific heat of water (4.18 J/g ºC) as the specific heat of the resulting solution.
Tungsten metal has a high strength-to-weight ratio and is known to withstand high temperatures, making it viable in military and marine industries. The molar heat capacity of tungsten is 24.3 J/mol ºC. Calculate the specific heat capacity of tungsten.
At constant pressure, the reaction C2H2(g) + 5/2 O2(g) → 2 CO2(g) + H2O releases 1255.8 kJ of energy. Provide the correct enthalpy diagram for the reaction.
Two solid objects, X and Y, were raised to a temperature of 150 ºC, Afterwards, each object was separated and placed in beakers with 500 g of water at 5.0 ºC. Object X raises the temperature of water by 5.3 ºC while object Y raises the temperature of water by 4.7 ºC. Identify the object with the larger specific heat.
The boiling point of a sample is 16 °C. A room-temperature (25 °C) surface is significantly cooled when the liquid form of the sample under pressure is sprayed on it. Which of the following statements is true based on this information?
The sun hits the Earth providing 172 W per square meter. A 1.29 m2 patch of a solid sample with an initial temperature of -3.80 °C is placed under the sun for 15.0 hours. If the sunlight uniformly penetrates the sample to a depth of 1.50 cm and it does not melt, what will be its final temperature? (enthalpy of fusion of liquid sample = 6.01 kJ/mol, specific heat capacity of solid sample = 2.032 J/g°C)
Consider two metal blocks, each weighing 250.0 g. One block is made of titanium and the other is made of platinum. Each block absorbed 16.34 kJ of heat. Identify which of the two metal blocks will have a higher rise in temperature. The molar heat capacities of Ti and Pt are 25.03 J/mol-°C and 25.86 J/mol-°C respectively.
Identify which between 1 mole water (H2O(l)) or 1 mole acetic acid (CH3COOH(l)) requires more heat to increase the temperature by 1 degree if the specific heat of acetic acid is 2.043 J/g-K
Calculate the molar heat capacity of manganese given its specific heat of 0.480 J/g-K.
Calculate the heat in J needed to raise the temperature of 100.0 g of acetone (C3H6O) from -25°C to 25°C considering that it has a specific heat of 2.15 J/g°C.
A specific type of coolant has a specific heat of 0.963 J/g-K which is actually lower than that of water. However, in terms of practicality, coolants can be better in certain situations. One property among others is having a much lower freezing point and much higher boiling point than water, which makes it more robust and has a higher temperature range for operating as a liquid. Considering that the coolant has a density of 1.79 g/mL, calculate the equivalent volume in gal of the coolant needed to provide the same heat capacity as 5.00 gal of water.
A block of titanium weighing 250.0 g was heated from 25.00 °C to 150.0 °C. The process required 16.34 kJ of heat. Calculate the molar heat capacity of titanium in J/mol-°C.
Two metals of the same weight are heated to 78.0°C and left in separate vacuum flasks. After 30 minutes, metal A is 75.0°C and metal B is 76.3 °C. Why did the two metals have different temperatures after 30 minutes?
A 26.0 g compound (molar mass = 85.00 g/mol) was dissolved in water with a final volume of 67.0 mL. If the temperature decreased from 24.7°C to 22.4°C, what is the change in enthalpy of the dissolution? (density solution = 1.09 g/mL, specific heat = 4.186 J/g•°C)
How much ice (ΔH°f = -291.8 kJ/mol) in grams is needed to decrease the temperature of 650 mL milk (density = 1.035 kg/L, C = 3.89 J/g•°C) from 75.0°C to 15.0°C?
How much butane gas (ΔcH°gas = -2878.3 kJ/mol ) in grams is needed to heat 400 mL of water from 15.0°C to 67.0 °C if only 45% of heat is transferred to the water?
Between fructose ,C6H12O6, (ΔH°f = -1265.6 kJ/mol) and lauric acid ,C12H24O2, (ΔH°f = −775.6 kJ/mol), which has more calories per gram after metabolism? Note: Metabolism of lauric acid and fructose produces water.
Calculate the heat capacity of 215 g of liquid water.
Which substance would have the greatest temperature change upon absorbing 200.0 J of heat?
a) 5.0 g NH3, CNH3 = 4.700 J/g°C
b) 5.0 g Li, CLi = 3.58 J/g°C
c) 5.0 g Fe, CFe = 0.412 J/g°C
d) 5.0 g H2O, CH2O = 4.181 J/g°C
e) 5.0 g Na, CNa = 1.230 J/g°C
A 25-gram sample of iron is initially at 25 °C. Calculate the final temperature if the sample absorbs 3.0 kJ of heat.
Calculate the amount of heat required to raise the temperature of 1.89 kg oil by 134 °C. The specific heat of the oil is 1.42 J/g • ºC.
A sample of gas with a mass of 50 g is heated from 20 °C to 300 °C while 300 J of work was done by the system, and its internal energy increased by 6000 J. Calculate the specific heat of the gas from the given information.
Calculate the amount of heat needed to raise the temperature of 2.00 L ethanol from 28.0°C to 78.3°C. The density of ethanol is 0.789 g/mL and its heat capacity is 2.42 J/g•°C.
A ceramic bowl has an initial temperature of 21.0°C and absorbs 1.62×103 J of heat. The final temperature recorded was 65.3°C. Calculate the mass of the ceramic bowl if it has a specific heat capacity of 0.323 J/g•°C.
A sample of titanium weighing 18.0 g has an initial temperature of 23.0°C. Determine the final temperature of the sample when it absorbs 3.18 kJ of heat. The specific heat capacity of titanium is 0.522 J/g•°C.
The enthalpy of fusion of water is 6.01 kJ/mol. Sunlight striking Earth's surface supplies 168 W per square meter (1 W = 1 watt = 1 J/s). The specific heat capacity of ice is 2.032 J/g°C. If the initial temperature of a 1.00 square meter patch of ice is −5.0°C, what is its final temperature after being in sunlight for 12 h, assuming no phase changes and assuming that sunlight penetrates uniformly to a depth of 1.00 cm?
Use standard enthalpies of formation to calculate the standard change in enthalpy for the melting of ice. (The ΔH °f for H2O(s) is -291.8 kJ/mol.) Use this value to calculate the mass of ice required to cool 355 mL of a beverage from room temperature (25.0 °C) to 0.0 °C. Assume that the specific heat capacity and density of the beverage are the same as those of water.
When 12.5 g of NH4NO3 is dissolved in 150.0 g of water of 25.0 °C in a coffee cup calorimeter, the final temperature of the solution of 19.7 °C. Assume that the specific heat of the solution is the same as that of water, 4.18 J/(g•°C). What is the ΔH per mol of NH4NO3?
NH4NO3 (s) → NH4+ (aq) + NO3−(aq) ΔH = ?
Suppose that 0.130 kg of a substance is initially at 25.0 °C. What is the final temperature of the substance upon absorbing 2.35 kJ of heat if its specific heat capacity is 0.456 J/g°C?
Instant cold packs are used to ice athletic injuries on the field by separating a thin plastic divider. It contains ammonium nitrate and water. When the divider is broken, the ammonium nitrate dissolves according to the endothermic reaction:
NH4NO3(s) → NH4+(aq) + NO3-(aq)
In the reaction, 2.55 g of NH4NO3 is dissolved in enough water to make 59.0 mL of solution. The initial temperature is 30.8 °C and the final temperature is 24.9 °C. Calculate the change in enthalpy for the reaction in kJ. (Use 1.0 g/mL as the density of the solution and 4.18 J/g°C as the specific heat capacity.)