A mixture is a system that is made up of two or more substances which are not combined chemically. A pure substance is a system that only has one substance. The following are classified as:
1.water : pure substance
<span>2.blood : mixture</span>
<span>3.the oceans : mixture</span>
<span>4.iron : pure substance
5.brass : mixture</span>
<span>6.uranium : pure substance</span>
<span>7.wine : mixture</span>
<span>8.leather : mixture</span>
<span>9.table salt (NaCl) : pure substance</span>
Energy transferred per second in given area:
8000 x 3.9 / 10000
Energy transferred = 3.12 J
Using Planck's equation:
E = nhc/λ
n = (3.12 x 510 x 10⁻⁹) / (3 x 10⁸ x 6.63 x 10⁻³⁴)
n = 8 x 10¹⁸ photons
Answer:
d) cut the large sized Cu solid into smaller sized pieces
Explanation:
The aim of the question is to select the right condition for that would increases the rate of the reaction.
a) use a large sized piece of the solid Cu
This option is wrong. Reducing the surface area decreases the reaction rate.
b) lower the initial temperature below 25 °C for the liquid reactant, HNO3
Hugher temperatures leads to faster reactions hence this option is wrong.
c) use a 0.5 M HNO3 instead of 2.0 M HNO3
Higher concentration leads to increased rate of reaction. Hence this option is wrong.
d) cut the large sized Cu solid into smaller sized pieces
This leads to an increased surface area of the reactants, which leads to an increased rate of the reaction. This is the correct option.
HF and NaF - If the right concentrations of aqueous solutions are present, they can produce a buffer solution.
<h3>What are buffer solutions and how do they differ?</h3>
- The two main categories of buffers are acidic buffer solutions and alkaline buffer solutions.
- Acidic buffers are solutions that contain a weak acid and one of its salts and have a pH below 7.
- For instance, a buffer solution with a pH of roughly 4.75 is made of acetic acid and sodium acetate.
<h3>Describe buffer solution via an example.</h3>
- When a weak acid or a weak base is applied in modest amounts, buffer solutions withstand the pH shift.
- A buffer made of a weak acid and its salt is an example.
- It is a solution of acetic acid and sodium acetate CH3COOH + CH3COONa.
learn more about buffer solutions here
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The rate of photosynthesis was measured by counting the amount of oxygen, a product of photosynthesis, generated by the plant. When the plant placed closer to the light source in a given time it generated more bubbles than when it was placed farther away from the light source.
