Answer:
The equilibrium temperature of the coffee is 72.4 °C
Explanation:
Step 1: Data given
Mass of cream = 15.0 grams
Temperature of the cream = 10.0°C
Mass of the coffee = 150.0 grams
Temperature of the coffee = 78.6 °C
C = respective specific heat of the substances( same as water) = 4.184 J/g°C
Step 2: Calculate the equilibrium temperature
m(cream)*C*(T2-T1) = -m(coffee)*c*(T2-T1)
15.0 g* 4.184 J/g°C *(T2 - 10.0°C) = -150.0g *4.184 J/g°C*(T2-78.6°C)
62.76T2 - 627.6 = -627.6T2 + 49329.36
690.36T2 = 49956.96
T2 = 72.4 °C
The equilibrium temperature of the coffee is 72.4 °C
Answer: B. Elements are represented by chemical formulas.
Elements are pure substances, which means that they cannot be broken down into simpler substances. The element is the most basic substance that exists, breaking it down further means breaking it down into protons, neutrons, and electrons, which is no longer a substance.
Elements have chemical properties that allow them to form different types of bonds with other elements.
However, elements *alone* are not represented by their chemical formulas. Only chemical bonds or ions are represented by a chemical formula.
Acid rain has no effect on limestone. So nothing happens.
Methylene blue indicates the presence of oxidizing agents because it is oxidized itself by these compounds. When electrons are stripped from methylene blue, the resulting molecule imparts a blue color to the solution--giving a clear sign of a chemical change.
