Answer:between 25 and 40 degrees Fahrenheit
Explanation:
Heat pumps do not operate as efficiently when temperatures drop to between 25 and 40 degrees Fahrenheit for most systems. A heat pump works best when the temperature is above 40. Once outdoor temperatures drop to 40 degrees, heat pumps start losing efficiency, and they consume more energy to do their jobs.
Chemical changes are considered unseen because they occur at the atomic level, changing the actual structure of the thing.
Answer:
Water has 18 grams per mole so 9 grams is 0.5 moles of water. There are 6.022* 10^23 molecules in a mole. Each water molecule contains one oxygen and two hydrogens.
Explanation:
the energy that that is needed to break a bond is called the bond energy or dissciation energy
The balanced chemical reaction for this would be written as:
2Mg + O2 = 2MgO
We use this reaction and the amount of the reactant given to calculate for the amount of magnesium oxide that is produced. We do as follows:
1.5 g Mg (1 mol / 24.31 g) ( 2 mol MgO / 2 mol Mg ) (40.30 g /1 mol ) = 2.49 g MgO produced