Answer:
Chemists investigate the properties of matter at the level of atoms and molecules. They measure proportions and reaction rates in order to understand unfamiliar substances and how they behave, or to create new compounds for use in a variety of practical applications.
Explanation:
Answer:
magnesium metal melts = physical change
magnesium metal ignites = chemical change
Explanation:
<em>Physical changes</em> are those in which the identity of the subtance <u>remains unaltered</u>. No new compounds are formed. They involve generally changes in <u>agreggation states of matter</u>: solid, liquid or gas. The first experiment, in which magnesium metal melts is a physical change because it only changes the state of matter, from solid to liquid, but it is still magnesium metal.
Conversely, <em>chemical changes</em> involve atoms combinations to form new compounds. The second experiment, in which magnesium metal ignites, is a chemical change. After the change, magnesium metal is no longer the metal but a metal oxide.
Answer:
The ability for a pond to freeze over in the winter is a physical property.
Answer:
A strong acid
Any strong acid (such as HCl, HBr, or 
) will completely dissociate forming a very weak conjugate base and H3O which will be acidic.
For this problem, we have to use the Planck's equation.
E = hv
where
E is the energy
h is Planck's constant equal to 6.626×10⁻³⁴ J·<span>s
v is the frequency in Hz or s</span>⁻¹<span>
Applying the equation, the answer would be:
E = (</span>6.626×10⁻³⁴ J·s)(5.49×10¹⁴ s⁻¹)
<em>E = 3.64×10⁻¹⁹ J</em>
