Answer:
2 moles H
2
Explanation:
Your tool of choice here will be the mole ratio that exists between zinc metal,
Zn
, and hydrochloric acid,
:HCl
, in the balanced chemical equation.
Zn
(s]
+
2
HCl
(aq]
→
ZnCl
2(aq]
+
H
2(g]
↑
⏐
You're dealing with a single replacement reaction in which zinc displaces the hydrogen from hydrochloric acid. The products of the reaction are aqueous zinc chloride and hydrogen gas.
Now, as you can see from the balance chemical equation, a
1
:
2
mole ratio exists between the two reactants.
This tells you that in order for the reaction to take place, you need to have twice as many moles of hydrochloric acid as you do of zinc metal.
http://people.springfield.k12.or.us/jim.tyser/chemcom/Resources/unit1ans.html
http://people.springfield.k12.or.us/jim.tyser/chemcom/Resources/unit1ans.html
At the same time, you have a
2
:
1
mole ratio between hydrochloric acid and hydrogen gas.
This means that the reaction will always produce half as many moles of hydrogen gas as you have moles of hydrochloric acid.
Since you know that
4
moles of hydrochloric acid are taking part in the reaction, and assuming that you have enough zinc metal so that it doesn't act as a limiting reagent, you can say that the reaction will produce
4
moles HCl
⋅
1 mole H
2
2
moles HCl
=
2 moles H
2
Explanation:
False! The three states of matter are solid, liquid, and gas. We can not touch gas, so it can not be compressed.
Answer: The element expected to be most electronegative is Ca.
The element expected to be least electronegative is K.
Explanation:
Electronegativity is defined as the property of an element to attract a shared pair of electron towards itself.
Down the group:
The size of an atom increases as we move down the group because a new shell is added and electron gets added up.
As, the size of an element increases, the valence electrons gets away from the nucleus. So, the attraction between the nucleus and the shared pair of electrons decreases
Hence, electronegativity decreases moving from top to bottom down a group
Across a period:
The size of an atom decreases as we move across the period because the electrons get added to the same shell and the nuclear charge keeps on increasing. Thus the electrons get more tightly held by the nucleus.
As, the size of an element decreases, the valence electrons come near to the nucleus. So, the attraction between the nucleus and the shared pair of electrons increases.
Hence, electronegativity increases moving across left to right in a period.
Thus as K, Sc and Ca are arranged across a period, the electronegativity order is K< Sc < Ca.
Answer:
60.12 miles
Explanation:
Using the calculation formula shown below:
![t_{1/2} =\frac{t}{[tex]log_{2}](https://tex.z-dn.net/?f=t_%7B1%2F2%7D%20%3D%5Cfrac%7Bt%7D%7B%5Btex%5Dlog_%7B2%7D)
\frac{N_{o} }{N_{t} } }[/tex]
where:
is the half life, 
is the original amount of F-18, and 
is the remaining amount of F-18 at time t.
Generally, F-18 has an half life of 1.83 hours.
Therefore:
![t = 1.83*[tex]log_{2}](https://tex.z-dn.net/?f=t%20%3D%201.83%2A%5Btex%5Dlog_%7B2%7D)
\frac{100}{68} = 1.02 hours[/tex]
Therefore using a speed of 59 miles/hour, the closeness of the hospital is:
distance = speed*time = 59*1.02 = 60.12 miles
As you get higher the atmospheric pressure lowers. The pressure in the packet of crisps has the pressure at which it has been closed (pressure at the surface of the earth). This means that the air molecules in the packet press harder outside than the air molecules in the atmosphere press on the packet.
