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2 years ago

Which of the following are compounds (select all that apply)

Chemistry

1 answer:

olga2289 [7]2 years ago

3 0

Answer:

KNO2, KBr

Explanation:

Chemical compounds are any substance composed of identical molecules consisting of atoms of two or more chemical elements. So NO2 and KBr are compounds, Br2 and Fe are not.

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A stock solution is 28.2 percent ammonia (NH3) by mass, and the solution has a density of 0.8990 grams per milliliter. What volu

Savatey [412]

Answer:

$\boxed{\text{20.2 mL}}$

Explanation:

Assume that the volume of the stock solution is 1 L.

1. Mass of stock solution

$\text{Mass} = \text{1000 mL} \times \dfrac{\text{0.8990 g}}{\text{1 mL}} = \text{899.0 g}$

2.Mass of NH₃

$\text{Mass of NH}_{3} = \text{899.0 g stock} \times \dfrac{\text{28.2 g NH}_{3}}{\text{100 g stock}} = \text{253.5 g NH}_{3}$

3. Moles of NH₃

$\text{Moles of NH}_{3} = \text{253.5 g NH}_{3}\times \dfrac{\text{1 mol NH}_{3}}{\text{17.03 g NH}_{3}}= \text{14.89 mol NH}_{3}$

4. Molar concentration of stock solution

$c = \dfrac{\text{moles}}{\text{litres}} = \dfrac{\text{14.89 mol}}{\text{1 L}} = \text{14.89 mol/L}$

5. Volume of stock needed for dilution

Now that you know the concentration of the stock solution, you can use the dilution formula .

$c_{1}V_{1} = c_{2}V_{2}$

to calculate the volume of stock solution.

Data:

c₁ = 14.89 mol·L⁻¹; V₁ = ?

c₂ = 0.500 mol·L⁻¹; V₂ = 600 mL

Calculations:

$\begin{array}{rcl}14.89V_{1} & = & 0.500 \times 600\\14.89V_{1} & = & 300\\V_{1} & = & \text{20.2 mL}\\\end{array}\\\text{You will need $\boxed{\textbf{20.2 mL}}$ of the stock solution.}$

4 0

3 years ago

What is the colour change that would be observed if carbon dioxide gas were bubbled into a mixture of calcium oxide, bromothymol

olya-2409 [2.1K]

Bromothymol blue is acid base indicator which has pH intervals 6 - 7.6 and its two colors are yellow in acid and blue in basic.
The pH of CaO is about 11.5 to 12.5 this will make the indicator has blue color at the beginning.
By bubbling CO₂ to CaO this leads to formation of CaCO₃ which also basic (pH about 9.5 - 10) so the color of indicator remains blue
No color change of the indicator will observed (remains blue)

8 0

3 years ago

What is reasoning in science?

loris [4]

Answer:

Scientific reasoning (SR), broadly defined, includes the thinking skills involved in inquiry, experimentation, evidence evaluation, inference and argumentation that are done in the service of conceptual change or scientific understanding.

6 0

3 years ago

No two different elements will have the atomic number.-

Alborosie

Answer:

True!

Explanation:

Atomic number is special for each element! For eg Hydrogen has atomic number 1, no other element has that atomic number besides Hydrogen

7 0

3 years ago

How do offspring inherit their traits?

Hatshy [7]

Answer:

Their parents share 1 gene each to the offspring's DNA

6 0

3 years ago