Upload a drawing: Construct a graph showing how the potential energy of the system changes as the distance between a positively-charged object and a negatively-charged object changes. (Hint: Will potential energy increase or decrease as the objects get closer together?) Potential energy distance between objects

A 27-gram piece of metal at 144  oC is dropped into 86 grams of water at 29 oC.  The water temperature rose to 37 oC.  Calculate the heat change of the metal in Joules.  (DO NOT PUT UNITS IN YOUR ANSWER.)  Assume that all of the heat lost by the metal is transferred to the water and no heat is lost to the surroundings.  The specific heat of water is 4.184 J / g oC.

Use your data to calculate the number of Calories in a 3.4 g sugar cube. (Molecular mass of sugar = 342.2965 g/mol; ΔHcomb sugar = 5639 kJ/mol; 1 Calorie = 1 Kcal)

Rachel West Section 017 A thermometer placed in a solution undergoing a chemical reaction indicates an increase in temperature as ie reaction proceeds. Is this reaction endorhermic or exothermic? Describe if heat energy is lost or gained Trom the reaction (the system) to the surroundings. What is the sign of the enthalpy change (AH) of this reaction? A student performs a reaction and determines the enthalpy change (AH) to be 31.4 kJ. Will the cemperature of the surrounding solution increase or decrease as a result of this chemical process?

A 21 gram piece of metal at 125 oC is dropped into 87 grams of water at 17 oC. The water temperature rose to 38 oC. Calculate the heat change of the metal in Joules. (DO NOT PUT UNITS IN YOUR ANSWER.) Assume that all of the heat lost by the metal is transferred to the water and no heat is lost to the surroundings. The specific heat of water is 4.184 J/g oC.

A 4.81 g sample of an unknown salt (MM = 116.82 g/mol) is dissolved in 150.00 g water in a coffee cup calorimeter. Before placing the sample in the water, the temperature of the salt and water is 23.72°C. After the salt has completely dissolved, the temperature of the solution is 28.54°C.   If 3.12 × 10³ J of heat was gained by the solution, what is the total heat for the dissolution reaction of the 4.81 g of salt?   How many moles of the unknown salt were used in the reaction ?     _______ J?

CH4 (g)  + 2 O2 (g)  -->  CO2 (g) + 2H2O (g)       Δ H = -882 kJ/mol   Using the equation above, how many grams of water will form if 655 kJ of energy was released.

The specific heat of substance C is 0.93 J/(g K) and that of substance D is 1.8 J/(g K). You are given an unknown that could be pure substance C, pure substance D, or a homogeneous mixture of C and D. In the lab you determine that it requires 23.3 J of heat energy to raise the temperature of a 25.0 g sample of the unknown by 1.0 K. What conclusions can you make about the identity of your unknown, from this data?

1. A thermometer placed in a solution undergoing a chemical reaction indicates an increase in temperature as the reaction proceeds. Is this reaction endothermic or exothermic? Describe if heat energy is lost or gained from the reaction (the system) to the surroundings. What is the sign of the enthalpy change (AH) of this reaction? 2. A student performs a reaction and determines the enthalpy change (AH) to be 31.4 kJ. Will the temperature of the surrounding solution increase or decrease as a result of this chemical process? 3. If you hold 3 grams of ice in your hand at room temperature, your hand will become cold. a) Is the reaction H,O(s) – H,O(1) endothermic or exothermic? b) In which direction does heat flow?

Suppose a boil water notice is sent out advising all residents in the area to boil their water before drinking it or using it for cooking. You need to boil 18.0 L of water using your natural gas (primarily methane) stove. What volume of natural gas is needed to boil the water if only 10.1% of the heat generated goes towards heating the water. Assume the density of methane is 0.668 g/L, the density of water is 1.00 g/mL, and that the water has an initial temperature of 21.4 °C. Enthalpy of formation values can be found in this table. Assume that gaseous water is formed in the combustion of methane.