Answer: pure substances.
Explanation:
The given substances are:
All what surrounds us, which has mass and occupies spaces, is matter. There are two kind of matter: pure substances and mixtures.
Pure substances have a uniform and constant composition. On the other hand, mixtures are combinations of two or more pure substances in any arbitratry ratio.
Pure substances may be elements or compounds. The elements are the substances conmposed by one only kind of atom. In the list of substances given, Li and O₂ are elements: all the atoms in Li are lithium, and all the atoms in O₂ are oxygen atoms.
Compounds are the chemical combination of two or more different kind of atoms. In the given list H₂O₂ and NaCl are compounds. As you see, H₂O₂ contains atoms of hydrogen and oxygen, chemically bonded, in a fixed ratio (2 atoms of hydrogen by 2 atoms of oxygen). And NaCl has atoms of Na (sodium) and Cl (chlorine), chemicaly bonded, in a fixed ratio (1:1).
There are only 118 known elements and you can find them in any modern periodic table. Therer are virtually infinitely many compounds since many different combinations of the elements can be attained.
Elements and compounds have in common that they are classified as pure substances.
Answer:
k = 0.0306 min-1
Explanation:
The table is given as;
Time, Concentration
0 1.48
5 1.27
10 0.98
15 0.84
The integrated rate law for a first order reaction is given as;
ln [A] = -kt + ln [Ao]
where;
[A] = Final Concentration
[Ao] = Initial Concentration
k = rate constant
t = time
In the table, taking the first two sets of values;
t = 5
k = ?
[Ao] = 1.48
[A] = 1.27
Inserting into the equation;
ln(1.27) = - k (5) + ln(1.48)
ln(1.27) - ln(1.48) = -5k
-0.1530 = -5k
k = -0.1530 / -5
k = 0.0306 min-1
This process is called aerobic respiration.
Answer:
The energy that is required for the process is:
6230.7 J + 42957 J + 9715.2 J = <u>58902.9 joules</u>
Explanation:
This is a calorimetry problem:
Q = m . C . ΔT
Q = heat; m = mas; C is the specific heat and
ΔT = Final T° - Initial T°
Q = C lat . m
Q = Heat
m = mass
C lar = Latent heat of fusion
First of all we calculate the heat for ice, before it takes the melting point. (from -23°C to 0°C)
Q = 129 g . 2.10 J/g°C . (0°C - (-23°C)
Q = 129 g . 2.10 J/g°C . 23°C → 6230.7 joules
Then, the ice has melted. To be melted and change the state it required:
Q = C lat . m
Q = 333 J/°C . 129 g → 42957 joules
And in the end, we have water that changed its T° from O°C to 18°C
Q = 129 g . 4.184 J/g °C . (18°C - 0°C)
Q = 9715.2 Joules
The energy that is required for the process is:
6230.7 J + 42957 J + 9715.2 J = 58902.9 joules
Answer: The volume of 
required is 25.0 ml
Explanation:
According to the neutralization law,
where,
= basicity 
= 1
= molarity of solution = 2.00 M
= volume of solution = 50.0 ml
= acidity of = 1
= molarity of solution = 4.00 M
= volume of solution = ?
Putting in the values we get:
Therefore, volume of required is 25.0 ml
