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3 years ago

Which of these substances are elements?

2 answers:

8 0

An element is a species of atom that has the same amounts of electrons and protons in their nuclei. To know which of these substances are elements, we can look it up in the periodic table of elements. The elements are as follows:

1.silicon
2.lead
3.silicone
5.iodine

Andru [333]3 years ago

8 0

Answer is:

1. silicon.

2. lead.

5. iodine.

Silicon (symbol: Si) is an element with atomic number 14 (14 protons).

Lead (Pb) is an element with atomic number 82.

Iodine (I) is an element with atomic number 53.

Silicone is a compound (polymer) made of silicon, oxygen, hydrogen, carbon and other elements.

Quartz is a compound (mineral) made of silicon and oxygen atoms.

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Considering 2N2H4(g) + N2O4(g) -> 3N2(g) +4H2O(g)

Tema [17]

Answer:

107.8

Explanation:

64 gram of N2H4 produce 72 gram of H20

then by crossmultiplication

64*121.3/72=107.82

3 0

3 years ago

The liquid dispensed from a burette is called ___________.

11Alexandr11 [23.1K]

The liquid that is been dispensed during titration as regards this question is Titrant.

Titration can be regarded as common laboratory method that is been carried out during quantitative chemical analysis.

This analysis helps to know the concentration of an identified analyte.

Burette can be regarded as laboratory apparatus.

It is used in the in measurements of variable amounts of liquid ,this apparatus helps in dispensation of liquid, especially when performing titration.

The specifications is been done base on their volume, or resolution.

The liquid that comes out of this apparatus is regarded as Titrant, and this is gotten during titration process, which is usually carried out during volumetric analysis.

Therefore, burrete is used in volumetric analysis.

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8 0

3 years ago

Read 2 more answers

How does adaption allow mice with the mutation to survive better in some areas

Debora [2.8K]

Answer: Mutations can cause instant adaptations, while natural selection is the process by which adaptations occurs over a series of generations. Adaptations are changes or processes of changes by which an organism or species becomes better suited for its environment. A mutation is an alteration of the DNA sequence.

3 0

3 years ago

Write the net ionic equation for the acid-base hydrolysis equilibrium that is established when ammonium perchlorate is dissolved

Whitepunk [10]

<u>Answer:</u> The net ionic equation is written below.

<u>Explanation:</u>

Net ionic equation of any reaction does not include any spectator ions.

Spectator ions are defined as the ions which do not get involved in the chemical equation. It is also defined as the ions which are found on both the sides of the chemical reaction when it is present in ionic form.

The chemical equation for the reaction of ammonium perchlorate and water is given as:

$NH_4ClO_4(aq.)+H_2O(l)\rightarrow NH_4OH(aq.)+HClO_4(aq.)$

Ionic form of the above equation follows:

$NH_4^+(aq.)+ClO_4^-(aq.)+H_2O(l)\rightarrow NH_4OH(aq.)+H^+(aq.)+ClO_4^-(aq.)$

Ammonium hydroxide will not dissociate into its ions because it is a weak base.

As, chlorate ions are present on both the sides of the reaction, thus, it will not be present in the net ionic equation.

The net ionic equation for the above reaction follows:

$NH_4^+(aq.)+H_2O(l)\rightarrow NH_3^+(aq.)+H_3O^+(aq.)$

Hence, the net ionic equation is given above.

5 0

3 years ago

In Part A, we saw that the theoretical yield of aluminum oxide is 1.60 mol . Calculate the percent yield if the actual yield of

garri49 [273]

Taking into account definition of percent yield, the percent yield for the reaction is 76.25%.

<h3>Percent yield</h3>

The percent yield is the ratio of the actual return to the theoretical return expressed as a percentage.

The percent yield is calculated as the experimental yield divided by the theoretical yield multiplied by 100%:

$percent yield=\frac{actual yield}{theorical yield}x100$

where the theoretical yield is the amount of product acquired through the complete conversion of all reagents in the final product, that is, it is the maximum amount of product that could be formed from the given amounts of reagents.

<h3>Percent yield in this case</h3>

In this case, you know:

actual yield= 1.22 mol
theorical yield= 1.60 mol

Replacing in the definition of percent yields:

$percent yield=\frac{1.22 mol}{1.60 mol}x100$

Solving:

<u><em>percent yield= 76.25%</em></u>

Finally, the percent yield for the reaction is 76.25%.

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4 0

2 years ago