Answer:
Chemical changes
Explanation:
a)Burning a piece of charcoal - chemical change
b) Heating copper (ii) carbonate strongly - chemical change
c) Heating Zinc oxide strongly - chemical change
The given types of reaction indicates chemical changes. A chemical change is one in which a new kind of matter is formed. It is always accompanied by energy changes. The process is not easily reversible and hence, it is a permanent procedure.
Burning of charcoal produces a new kind of produces in the combustion process.
Both heating of copper(ii)carbonate strongly and zinc oxide will lead to a decomposition reaction in which new compounds are formed.
The answer is: 8.14·10⁶³ moles of lithium are present.
N(Li₂SO₄) = 2.45·10⁸⁷; number of formula units of lithium sulfate.
n(Li₂SO₄) = N(Li₂SO₄) ÷ Na.
n(Li₂SO₄) = 2.45·10⁸⁷ ÷ 6.022·10²³ 1/mol.
n(Li₂SO₄) = 4.07·10⁶³ mol; amount of lithium sulfate
In one molecule of lithium sulfate, there are two atoms of lithium.
n(Li₂SO₄) : n(Li) = 1 : 2.
n(Li) = 2 · 4.07·10⁶³ mol.
n(Li) = 8.14·10⁶³ mol; amount of lithium atoms.
Answer:
518.52K
Explanation:
Charles law, which describes the direct relationship between the volume and the temperature of a gas when the pressure is constant, will be used for this question. The Charles law equation is:
V1/T1 = V2/T2
Where; V1 is the volume of the gas at an initial state (Litres)
T1 is the absolute temperature of the gas at an initial state (Kelvin)
V2 is the volume of the gas at a final state (Litres)
T2 is the absolute temperature of the gas at a final state (Kelvin)
According to the question, V1 = 2.3L, T1 = 25°C, V2 = 4L, T2 = ?
We need to convert the temperature to the absolute temperature unit in Kelvin (K) i.e.
T(K) = T(°C) + 273.15
T(K) = 25°C + 273.15
T1 (K) = 298.15K
To find for T2 in the equation, we make T2 the subject of the formula:
T2 = V2 × T1 / V1
T2 = 4 × 298.15 / 2.3
T2 = 1192.6/2.3
T2 = 518.52
Thus, the temperature must be heated to 518.52K in order to expand to a volume of 4L. This answer is in accordance to Charles law that the volume increases with increase in temperature and vice versa.
Test the hypothesis in an expirement!
