Answer:
2.07 Kcal heat must be added to completely melt the platinum.
Explanation:
Given data:
Molar heat of fusion = 4.700 Kcal / mol
Mass of platinum = 85.5 g
Heat of fusion = ?
Solution:
Formula:
ΔH = n × molar heat of fusion
n = number of moles
Now we will calculate the number of moles:
Number of moles = mass / molar mass
Number of moles = 85.5 g /195.08 g/mol
Number of moles = 0.44 mole
ΔH = n × molar heat of fusion
ΔH = 0.44 mol × 4.700 Kcal / mol
ΔH = 2.07 Kcal
Answer:
No, in science their meanings are not the same as their everyday meanings.
Explanation:
In Science, Precision and Accuracy are defined as,
Accuracy:
Accuracy is the value which is closest to the known or standard value.
Precision:
While, Precision is the value of closeness of two measured values to each other.
Example:
Let suppose in Chemistry Lab you weight an object as 50 g. While the actual weight of that object is 30 g. It means your reading is not accurate.
On second measurement you find that the object weight is 31 g. This time your reading is not precise.
Answer:
Hydrogen is placed above group in the periodic table because it has ns1 electron configuration like the alkali metals. However, it varies greatly from the alkali metals as it forms cations (H+) more reluctantly than the other alkali metals.
Explanation:
The molecular formula for Hydrocarbon = C₄H₁₀
<h3>
Further explanation:</h3>
Given
50 ml hydrocarbon
200 ml CO₂
250 ml H₂O
Required
The molecular formula of Hydrocarbon
Solution
From Avogadro's hypothesis, at the same temperature and pressure, the ratio of gas volume will be equal to the ratio of gas moles
So moles Hydrocarbon : CO₂ : H₂O = 50 ml : 200 ml : 250 ml = 1 : 4 : 5
mol C in 1 mol CO₂=1, and for 4 moles CO₂ there are 4 moles C
mol H in 1 mol H₂O =2, and for 5 moles H₂O there are 10 moles H
So mol ratio C : H in compound = C₄H₁₀
Answer:
A lithium atom has 3 protons and 3 electrons. It can lose one of its electrons, making it an ion. It now has more positive protons than electrons so it has an overall positive charge. Therefore it is a positive ion.
Explanation:
Lithium, an alkali metal with three electrons, is also an exception to the octet rule. Lithium tends to lose one electron to take on the electron configuration of the nearest noble gas, helium, leaving it with two valence electrons.
