Answer:
C The experiment shows that the red substance experienced a chemical change.
Explanation:
Apparently, adding heat caused the red substance to decompose into a gas and a metallic liquid. If it were simply a phase change, the original red substance could be expected to return when the temperature cooled. Because the substance apparently decomposed, it is clearly not an element. At no point in the experiment is there any evidence of a plasma being formed.
The observed decomposition is a chemical change.
The reaction is as follows:
2 H₂(g) + O₂(g) → 2 H₂O(g) . ΔH = - 483.5 kJ
Using the change in enthalpy and heat, calculate the moles as follows:
Moles of H₂ = -
x 2 mol H₂
= - 216 kJ / (-483.5 kJ) x 2 mol H₂
= 0.893 mol H₂
Calculate the mass of H₂ using the moles and molar mass as follows:
0.893 mol H₂ x (2.02 g H₂ / 1 mol H₂) = 1.79 g H₂
Therefore, the mass of hydrogen gas is 1.79 g
Answer:
2H₂O₂ → 2H₂O + O₂
24.7 L are the liters of formed oxygen.
Explanation:
We state the reaction:
2H₂O₂ → 2H₂O + O₂
2 moles of peroxide decompose to 2 moles of water and 1 mol of oxygen gas.
We convert the mass to moles: 75 g . 1 mol / 34 g = 2.20 moles
As ratio is 2:1, per 2.20 moles of peroxide I would produce the half of moles, of O₂ → 2.20 /2 = 1.10 moles
We convert the moles to mass → 1.10 mol . 32 g / 1 mol = 35.3 g
Let's use oxygen's density to find out the volume
δ O₂ = 1.429 g/L (mass/volume)
35.3 g . 1L / 1.429g = 24.7 L
Answer:
Atomic models are important because, they help us visualize the interior of atoms and molecules, and thereby predicting properties of matter.
Explanation:
We study the various atomic models in our course of study because, it is important for us to know, how did people come to the present concept of an atom. How did physics evolve from classical to quantum physics.
All these are important for us to know and thus, knowledge about various atomic models, their discoveries and drawbacks and finally improvements based on scientific evidence present at that time is important for us to understand the underlying theory very well.
Answer:
A
Explanation:
In genetic terms, a dominant trait is one that is phenotypically expressed in heterozygotes
