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Gelneren [198K]

1 year ago

7

Liquid nitrogen has different properties from gaseous nitrogen. Is it a chemical change when liquid nitrogen warms to gaseous ni

trogen?

2 answers:

castortr0y [4]1 year ago

7 0

No, it is a physical change

bezimeni [28]1 year ago

3 0

No, it is a physical change. Changing states is physical.A chemical change is to change the nature of something by changing it's chemical makeup.

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How may the use of less fertilizers on plants and lawns help the chesapeake bay and other estuaries?

CaHeK987 [17]

As land use<span> patterns change and the watershed's population grows, the amount of ... </span>Other<span> solutions to nitrogen and phosphorus pollution include upgrading stormwater ... on septic systems, and decreasing </span>fertilizer<span> applications to </span><span>lawns</span>

3 0

1 year ago

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Calculate the energy difference for a transition in the paschen series for a transition from the higher energy shell n=4. expres

Troyanec [42]

Electrons are orbiting around the nucleus in a specific energy level as described in Bohr's atomic model. There are 7 energy levels all in all; 1 being the strongest and nearest to the nucleus, and 7 being the weakest and farthest away from the nucleus. Electron can transfer from one energy level to another. If it increases energy, it absorbs energy. If it goes down an energy level, it emits energy in the form of light. This light can be measure in wavelength through the Rydberg equation:

1/λ =R(1/n₁² -1/n₂²), where
λ is the wavelength
R is the Rydberg constant equal to 1.097 × 10⁻7<span> per meter
n</span>₁ and n₂ are the energy levels such that n₂>n₁

In the Paschen series is an emission spectrum of hydrogen when the energy level is at least n=4. So, this covers n=4 to n=7.

1/λ =(1.097 × 10⁻7)(1/4² -1/7²)
λ = 216.57 ×10⁻⁶ m or 216.57 μm

5 0

1 year ago

The structure of carbonic acid, an important component of ocean chemistry, is depicted below. What type of model best describes

BabaBlast [244]

Answer: Option (c) is the correct answer.

Explanation:

A physical model is defined as a model which represents how atoms are bonded together and structure of a molecule.

Physical model shows the three dimensional structure of a molecule. Physical models helps to easily understand and visualize the configuration, single bonds, double bonds and total atoms within a molecule.

Thus, we can conclude that given structure of carbonic acid best describes a physical model.

4 0

1 year ago

Read 2 more answers

A scientist has isolated a chemical compound that is partially soluble in water. The chemical helps keep water-soluble substance

VLD [36.1K]

Answer:

Based on the information, the compound is a phospholipid.

Explanation:

Phospholipids are made up of a fatty acid tail which is hydrophobic in nature and a head which comprises of phosphates that is hydrophilic in nature. Hence, phospholipids are amphiphilic compounds so they will be partially soluble in water and will allow water-soluble substances to mix with fats.

Hence, the composition of the substance described in the question confirms that is a phospholipid. As it's structure contains hydrocarbon and phosphorus and might also contain nitrogen.

4 0

1 year ago

Which balanced redox reaction is occurring in the voltaic cell represented by the notation of A l ( s ) | A l 3 ( a q ) | | P b

frez [133]

The question is missing. Here is the complete question.

Which balanced redox reaction is ocurring in the voltaic cell represented by the notation of $Al_{(s)}|Al^{3+}_{(aq)}||Pb^{2+}_{(aq)}|Pb_{(s)}$ ?

(a) $Al_{(s)}+Pb^{2+}_{(aq)} ->Al^{3+}_{(aq)}+Pb_{(s)}$

(b) $2Al^{3+}_{(aq)}+3Pb_{(s)} -> 2Al_{(s)}+3Pb^{2+}_{(aq)}$

(c) $Al^{3+}_{(aq)}+Pb_{(s)} ->Al_{(s)}+Pb^{2+}_{(aq)}$

(d) $2Al_{(s)}+3Pb^{2+}_{(aq)} -> 2Al^{3+}_{(aq)}+3Pb_{(s)}$

Answer: (d) $2Al_{(s)}+3Pb^{2+}_{(aq)} -> 2Al^{3+}_{(aq)}+3Pb_{(s)}$

Explanation: <u>Redox</u> <u>Reaction</u> is an oxidation-reduction reaction that happens in the reagents. In this type of reaction, reagent changes its oxidation state: when it loses an electron, oxidation state increases, so it is oxidized; when receives an electron, oxidation state decreases, then it is reduced.

Redox reactions can be represented in shorthand form called <u>cell</u> <u>notation,</u> formed by: <em><u>left side</u></em> of the salt bridge (||), which is always the <em><u>anode</u></em>, i.e., its half-equation is as an <em><u>oxidation</u></em> and <em><u>right side</u></em>, which is always <em><u>the cathode</u></em>, i.e., its half-equation is always a <em><u>reduction</u></em>.

For the cell notation: $Al_{(s)}|Al^{3+}_{(aq)}||Pb^{2+}_{(aq)}|Pb_{(s)}$

Aluminum's half-equation is oxidation:

$Al_{(s)} -> Al^{3+}_{(aq)}+3e^{-}$

For Lead, half-equation is reduction:

$Pb^{2+}_{(aq)}+2e^{-} -> Pb_{(s)}$

Multiply first half-equation for 2 and second half-equation by 3:

$2Al_{(s)} -> 2Al^{3+}_{(aq)}+6e^{-}$

$3Pb^{2+}_{(aq)}+6e^{-} -> 3Pb_{(s)}$

Adding them:

$2Al_{(s)}+3Pb^{2+}_{(aq)} -> 2Al^{3+}_{(aq)}+3Pb_{(s)}$

The balanced redox reaction with cell notation $Al_{(s)}|Al^{3+}_{(aq)}||Pb^{2+}_{(aq)}|Pb_{(s)}$ is

$2Al_{(s)}+3Pb^{2+}_{(aq)} -> 2Al^{3+}_{(aq)}+3Pb_{(s)}$

6 0

2 years ago