Answer:
Reaction 5: Decomposition reaction.
Reaction 6: Single replacement reaction
Reaction 7: Combination reaction.
Reaction 8: Combustion reaction.
Explanation:
<u><em>Reaction 5:</em></u> 2KClO₃ → 2KCl + 3O₂.
- It is a decomposition reaction.
- A decomposition reaction is a type of chemical reaction in which a single compound breaks down into two or more elements or new compounds.
- In this reaction: potassium chlorate decomposes into two single components (potassium chloride and oxygen).
- So, it is a decomposition reaction.
<u><em>Reaction 6:</em></u> Zn + 2HCl → H₂ + ZnCl₂.
- It is a single replacement reaction.
- A single-replacement reaction, a single-displacement reaction, is a reaction by which one (or more) element(s) replaces an/other element(s) in a compound.
- It is most often occur if element is more reactive than the other, thus giving a more stable product.
- In this reaction, zinc metal (more active) displaces the hydrogen to form hydrogen gas and zinc chloride, a salt. Zinc reacts quickly with the acid to form bubbles of hydrogen.
<u><em>Reaction 7:</em></u> N₂O₅ + H₂O → 2HNO₃.
- It is a combination "synthesis" reaction.
- A synthesis reaction has two or more reactants and only one product.
- In this reaction, dinitrogen pentoxide reacts with water to produce nitric acid.
- So, it is considered as a synthetic "combination" reaction.
<u><em>Reaction 8:</em></u> 2C₂H₆ + 7O₂ → 4CO₂ + 6H₂O.
- It is a combustion reaction.
- A combustion reaction is a reaction where hydrocarbon alkane is completely burned in oxygen to produce water and carbon dioxide.
- In this reaction 1.0 mole of ethane is burned to give 4.0 moles of carbon dioxide and 6.0 moles of water.
- So, it is considered as a combustion reaction.
Answer: a. two substances present; two phases present : Heterogeneous mixture
b. two substances present; one phase present
: Homogeneous mixture
c. one substance present; one phase present
: pure substance.
d. one substance present; two phases present: Heterogeneous mixture
Explanation:
A pure substance is a substance which contains definite composition of only one type of component. Hence, it cannot be separated by physical means.
Mixture is a substance which contains two or more than two types of components and they can be separated by physical means as well.
Homogeneous mixtures: It is a mixture that has uniform composition throughout the solution and the particle size or shapes are not different. There is no physical boundary between the dispersed phase and dispersion medium.
Heterogeneous mixtures: It is a mixture that has non-uniform composition throughout the solution and the particle size or shapes are also different. There is a physical boundary between the dispersed phase and dispersion medium.
Answer:
248 mL
Explanation:
According to the law of conservation of energy, the sum of the heat absorbed by water (Qw) and the heat released by the coffee (Qc) is zero.
Qw + Qc = 0
Qw = -Qc [1]
We can calculate each heat using the following expression.
Q = c × m × ΔT
where,
- ΔT: change in the temperature
163 mL of coffee with a density of 0.997 g/mL have a mass of:
163 mL × 0.997 g/mL = 163 g
From [1]
Qw = -Qc
cw × mw × ΔTw = -cc × mc × ΔTc
mw × ΔTw = -mc × ΔTc
mw × (54.0°C-25.0°C) = -163 g × (54.0°C-97.9°C)
mw × 29.0°C = 163 g × 43.9°C
mw = 247 g
The volume corresponding to 247 g of water is:
247 g × (1 mL/0.997 g) = 248 mL
The molecules vibrate faster and space between atoms increase
It's called Ice Wedging :)
