The correct answer should be A.Ca and Br. A salt consists of a metal and a nonmetal, and a positive and negative charge. Ca (Calcium) is a metal and Br (Bromine) is a nonmetal, Ca is a +2 charge and Br is a -1 charge, so this is the only correct answer. Hope this helps :)
Displaced volume :
<span> Vf - Vi
</span>
77.0 mL - 50.0 mL => 27 mL
Therefore:
d = m / V
d = 521 / 27
d = 19.29 g/mL
Answer:
Explanation:
a) In an exothermic reaction, the energy transferred to the surroundings from forming new bonds is ___more____ than the energy needed to break existing bonds.
b) In an endothermic reaction, the energy transferred to the surroundings from forming new bonds is ___less____ than the energy needed to break existing bonds.
c) The energy change of an exothermic reaction has a _____negative_______ sign.
d) The energy change of an endothermic reaction has a ____positive________ sign.
The energy changes occur during the bonds formation and bonds breaking.
There are two types of reaction endothermic and exothermic reaction.
Endothermic reactions:
The type of reactions in which energy is absorbed are called endothermic reactions.
In this type of reaction energy needed to break the bond are higher than the energy released during bond formation.
For example:
C + H₂O → CO + H₂
ΔH = +131 kj/mol
it can be written as,
C + H₂O + 131 kj/mol → CO + H₂
Exothermic reaction:
The type of reactions in which energy is released are called exothermic reactions.
In this type of reaction energy needed to break the bonds are less than the energy released during the bond formation.
For example:
Chemical equation:
C + O₂ → CO₂
ΔH = -393 Kj/mol
it can be written as,
C + O₂ → CO₂ + 393 Kj/mol
