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3 years ago

I NEED HELP PLEASE JUST 3 QUESTIONS.

Chemistry

1 answer:

disa [49]3 years ago

4 0

1. Soil serves as a:

medium for plant growth,

regulator of water supplies,

recycler of raw materials,

habitat for soil organisms, and.

landscaping and engineering medium.

2. Soil organisms, which range in size from microscopic cells that digest decaying organic material to small mammals that live primarily on other soil organisms, play an important role in maintaining fertility, structure, drainage, and aeration of soil.

3. Advances in watershed, natural resource, and environmental sciences have shown that soil is the foundation of basic ecosystem function. Soil filters our water, provides essential nutrients to our forests and crops, and helps regulate the Earth's temperature as well as many of the important greenhouse gases.

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A solid reactant is placed into a beaker of a warm water. The liquid vigorously bubbles as the solid dissolves into the solution

Andrej [43]

Answer:

Fewer bubbles will be produced because of fewer collisions of reactant molecules

Explanation:

As the solid dissolves into the solution after the liquid has been vigorously bubbled, if the temperature of the liquid is reduced a little, what will happen is that fewer bubbles will be produced as a result of lesser amount of collisions occurring between the reactant molecules

3 0

3 years ago

Read 2 more answers

Can someone help me please??

Xelga [282]

41) Answer is: the average atomic mass of chromium is 52.056.

Ar(⁵⁰Cr) = 50.

ω(⁵⁰Cr) = 4.34% ÷ 100%.

ω(⁵⁰Cr) = 0.0434; relative abundance of chromium-50.

Average mass can calculate by summary of percentege of each isotope.

Ar(Cr) = Ar(⁵⁰Cr) · ω(⁵⁰Cr) + Ar(⁵²Cr) · ω(⁵²Cr) + Ar(⁵³Cr) · ω(⁵³Cr) + Ar(⁵⁴Cr) · ω(⁵⁴Cr).

Ar(Cr)= 50 · 0.0434 + 52 · 0.8379 + 53 · 0.095 + 54 · 0.0237.

Ar(Cr) = 2.17 + 43.571 + 5.035 + 1.280

Ar(Cr) = 52.056.

42) Chlorine has atomic number 17, it means it has 17 protons and 17 electrons.

Electron configuration of chlorine atom: ₁₇Cl 1s² 2s² 2p⁶ 3s² 3p⁵.

Chloride is negative ion of chlorine. Chloride is formed when chlorine gain one lectron.

Chloride anion has 17 protons and 18 electrons (like argon-noble gas).

The electron configuration for the chloride ion: ₁₇Cl⁻ 1s²2s²2p⁶3s²3p⁶.

43) Anwser is: the percent by mass of hydrogen in aspirin is 4.48%.

% calculate by atomic mass of element multiply number of that element in molecule divided by molecular mass of molecule.

Ar(H) = 1.008; the relative atomic mass of hydrogen atom.

Mr(C₉H₈O₄) = 9 · Ar(C) + 8 · Ar(H) + 4 · Ar(O).

Mr(C₉H₈O₄) = 180.157.

ω(H)= 8 · Ar(H) ÷ Mr(C₉H₈O₄) · 100%.

ω(H) = 8 · 1.008 ÷ 180.157 · 100%.

ω(H) = 4.48 %.

44) Balanced chemical reaction:

Cd(NO₃)₂ + 2NH₄Cl → CdCl₂ + 2NH₄NO₃.

This chemical reaction is double displacement reaction - cations (Cd²⁺ and NH₄⁺) and anions (NO₃⁻ and Cl⁻) of the two reactants switch places and form two new compounds.

Cd(NO₃)₂ is cadmium nitrate.

NH₄Cl is amonium chloride.

CdCl₂ is cadmium chloride.

NH₄NO₃ is ammonium nitrate.

4 0

4 years ago

The bond dissociation energy to break 4 bond(s) in 1 mole of CH₄ molecules is:_____ **Any help would be greatly appreciated!**

frozen [14]

Answer:

The bond dissociation energy to break 4 bonds in 1 mol of CH is 1644 kJ

Explanation:

Since there are 4 C-H bonds in CH₄, the bond dissociation energy of 1 mol of CH₄ is 4 × bond dissociation energy of one C-H bond.

From the table one mole is C-H bond requires 411 kJ, that is 411 kJ/mol. Therefore, 4 C-H bonds would require 4 × 411 kJ = 1644 kJ

So, the bond dissociation energy to break 4 bonds in 1 mol of CH₄ is 1644 kJ

5 0

3 years ago

When 21.45 g of KNO3 was dissolved in water in a calorimeter, the temperature fell from 25.00°C to 14.14 °C. If the heat capacit

pashok25 [27]

25.9 kJ/mol. (3 sig. fig. as in the heat capacity.)

<h3>Explanation</h3>

The process:

$\text{KNO}_3\;(s) \to \text{KNO}_3\;(aq)$ .

How many moles of this process?

Relative atomic mass from a modern periodic table:

K: 39.098;
N: 14.007;
O: 15.999.

Molar mass of $\text{KNO}_3$ :

$M(\text{KNO}_3) = 39.098 + 14.007 + 3\times 15.999 = 101.102\;\text{g}\cdot\text{mol}^{-1}$ .

Number of moles of the process = Number of moles of $\text{KNO}_3$ dissolved:

$\displaystyle n = \frac{m}{M} = \frac{21.45}{101.102} = 0.212162\;\text{mol}$ .

What's the enthalpy change of this process?

$Q = C\cdot \Delta T = 0.505 \times (25.00 - 14.14) = 5.4843\;\text{kJ}$ for $0.212162\;\text{mol}$ . By convention, the enthalpy change $\Delta H$ measures the energy change for each mole of a process.

$\displaystyle \Delta H = \frac{Q}{n} = \frac{5.4843\text{kJ}}{0.212162\;\text{mol}} = 25.8\;\text{kJ}\cdot\text{mol}^{-1}$ .

The heat capacity is the least accurate number in these calculation. It comes with three significant figures. As a result, round the final result to three significant figures. However, make sure you keep at least one additional figure to minimize the risk of rounding errors during the calculation.

4 0

3 years ago

Why is U-235 the most common nuclear fuel instead of the more abundant U-238? State a clear topic sentence and support it with e

GREYUIT [131]

<h3><u>Answer and explanation</u>;</h3>

<em><u>The isotope U-235 is an important common nuclear fuel because under certain conditions it can readily be split, yielding a lot of energy. It is therefore said to be 'fissile' and use the expression 'nuclear fission'.</u></em>
<em><u>Uranium 238 on the other hand is not fissionable by thermal neutrons, but it can undergo fission from fast or high energy neutrons. Hence it is not fissile, but it is fissionable.</u></em>
In a nuclear power station fissioning of uranium atoms replaces the burning of coal or gas. Heat created by splitting the U-235 atoms is then used to make steam which spins a turbine to drive a generator, producing electricity.

3 0

3 years ago