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
Answer:
m = 700 g
Explanation:
Density:
Density is equal to the mass of substance divided by its volume.
Units:
SI unit of density is Kg/m3.
Other units are given below,
g/cm3, g/mL , kg/L
Formula:
D=m/v
D= density
m=mass
V=volume
Symbol:
The symbol used for density is called rho. It is represented by ρ. However letter D can also be used to represent the density.
Given data:
Density of octane = 0.700 g/cm³
Volume = 1 L
Mass = ?
Formula:
D=m/v
D= density
m=mass
V=volume
First of all we will convert the volume in cm³ because density is given in g/cm³ unit.
1 L = 1000 cm³
Now we will put the values in formula:
d= m/v
m = v × d
m = 1000 cm³ × 0.700 g/cm³
m = 700 g
Answer:
1.60.
Explanation:
- The no. of millimoles of HCl = MV = (0.15 M)(20.0 mL) = 3.0 mmol.
- The no. of millimoles of KOH = MV = (0.10 M)(20.0 mL) = 2.0 mmol.
<em>Since the no. of millimoles of HCl is larger than that of KOH. The solution is acidic.</em>
<em></em>
∴ M of remaining HCl [H⁺] remaining = (NV)HCl - (NV)KOH/V total = (3.0 mmol) - (2.0 mmol) / (40.0 mL) = 0.025 M.
∵ pH = - log[H⁺]
<em>∴ pH = - log[H⁺] </em>= - log(0.025) = <em>1.602 ≅ 1.60.</em>
4 moles of water are produced
Explanation:
- 4 moles of water are produced when 5 moles of hydrogen is reacted with 2 moles of oxygen gas
- The balanced equation given is when 2 moles of hydrogen reacts with 1 mole of oxygen and it forms 2 moles of water.
- The equation we have to solve is the 5 moles of hydrogen is reacting with 2 moles of oxygen gas, we can write the equation as
- This is the balanced equation when 5 moles of hydrogen reacts with 2 moles of oxygen. The balanced equation means the number of hydrogen atoms and oxygen atoms on both sides would be equal in number.
1 hectoliter is 26.4172
1 kiloliter is 264.172
