1)an unknown solution is heated from 25°c to 78°c. it has a mass of 3.98g. solve for the unknown variables. is the reaction endothermic, or exothermic? 2) over time a solution has a final temperature of -35°c, and a change in temperature of 5°c. what state of matter is the substance? is the reaction endothermic, or exothermic? 3) a frozen glass of water is placed in a freezer, and becomes 25°c colder than its original temperature. it has a volume of 23.8g. how much energy was converted? was this endothermic, or exothermic? 4) a 8g glass of water has evaporated and it’s content is floating in a locked container. when you find the container it is at 125°c, you begin to cool the container and then find a temperature of 105°c. what is the enthalpy of said rxn? 5) how much energy was used to convert 45g of water from a solid to a liquid?

The last few miles of the marathon are the most difficult for heather, her hair plastered to her head, sweat clinging to her arms, and her legs already feeling as if they had nothing left, just dead weight. after grabbing a cup of ice water, she feels the ice cubes smash against her nose as she gulps some cool refreshment and keeps on running. in these last few miles, the breeze kicks up and she finally feels some coolness against her skin. drips of sweat, once clinging to her forehead, now spill down, and heather feels more pain as the sweat flows into her eyes.which of the following is the most likely reason why the ice struck heather’s nose when she took a drink? a) water can function as a solvent. b) water can store large amounts of heat. c) water can moderate temperatures through evaporative cooling. d) the density of water decreases when it freezes. e) water has a cohesive nature.sweat remained on heather’s forehead and arms because of the a) high salt content of sweat b) cohesive nature of water c) ability of water to moderate heat d) high evaporative cooling effect of water e) ability of water to act as a solvent

8.98 dm3 of hydrogen gas is collected at 38.8 °c. find the volume the gas will occupy at -39.9 °c if the pressure remains constant.

Which of these statements best explains why space exploration should be encouraged? it prepares humans to live without oxygen. it dispel myths about objects in space. it prevents comets and asteroids from striking earth. it creates technology to absorb harmful radiations in space.