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Por favor, me ajudem.

Please, help me.

Someone can teach me English, because I'm from Brazil and if you know how to speak Spanish, it's better for me.

Answer:

Scientific method.

Explanation:

Scientific method is the way taken to acquire scientific knowledge. It includes experiments, statistical analysis of existing data, and all kinds of observations of the world around us, while theoretical research is based on deriving certain theories about the world from basic principles, in a mathematical or logical way. The scientific method applies to both types of research, and emphasizes that scientific research is objective, that it can be verified by other scientists, and that knowledge is not acquired without context, but in a way that leads to a greater understanding of previous research and the world. we live in. To contribute to this, researchers are expected to clearly record both their findings and the methods they use to arrive at the results.

Answer:

19000 torr

Explanation:

From the question given above, the following data were obtained:

Initial volume (V₁) = 0.150 L

Initial pressure (P₁) = 1520 torr

Final volume (V₂) = 0.012 L

Temperature = constant

Final pressure (P₂) =?

The final pressure of the gas can be obtained by using the Boyle's law equation as illustrated below:

P₁V₁ = P₂V₂

1520 × 0.150 = P₂ × 0.012

228 = P₂ × 0.012

Divide both side by 0.012

P₂ = 228 / 0.012

P₂ = 19000 torr

Thus, the final pressure of the gas is 19000 torr

Answer:

Surely with water

Ok, but how?

There are many Hydrogen Bond between H2O moleculs and london bonds. When fishes take water with their gill,they are broke london bonds. And they can take their needs, Oxygen. Only this.

Good luck :D

Answer:

0.0900 mol/L

Explanation:

A chemist makes 330. mL of nickel(II) chloride working solution by adding distilled water to 220. mL of a 0.135 mol/L stock solution of nickel(II) chloride in water. Calculate the concentration of the chemist's working solution. Round your answer to significant digits.

Step 1: Given data

Step 2: Calculate the concentration of the final solution

We prepare a dilute solution from a concentrated one. We can calculate the concentration of the working solution using the dilution rule.

C₁ × V₁ = C₂ × V₂

C₂ = C₁ × V₁/V₂

C₂ = 0.135 mol/L × 220. mL/330. mL = 0.0900 mol/L

Answer:

n = 2.23 moles

Explanation:

Given the following data;

Standard temperature = 273 K

Standard pressure = 101.325 kPa

Volume = 50 liter

R = 8.314 J/mol·K  

To find the number of moles, we would use the ideal gas law formula;

PV = nRT

Where;

Making n the subject of formula, we have;

[tex] n = \frac {PV}{RT} [/tex]

Substituting into the formula, we have;

[tex] n = \frac {101.325*50}{8.314*273} [/tex]

[tex] n = \frac {5066.25}{2269.722} [/tex]

n = 2.23 moles

Therefore, 2.23 moles of carbon dioxide at STP will fit in a 50 liter container.

Answer:

No mass of HCl could be left over by the chemical reaction because is the limting reactant and it is all consumed.

Explanation:

Our reactants are: HCl and NaOH

Products are: NaCl and H₂O

This is a neutralization reaction that can also be called an acid base reaction, an acid and a base react to produce water and a neutral salt, in this case where we have strong acid and base.

Ratio is 1:1. We convert mass to moles:

35 g . 1 mol / 36.45 g = 0.960 moles of HCl

73 g . 1 mol / 40 g = 1.82 moles of NaOH

As ratio is 1:1, for 0.960 moles of HCl we need 0.960 moles of NaOH and for 1.82 moles of NaOH, we need 1.82 moles of acid.

As we only have 0.960 moles of HCl and we need 1.82 moles, no acid remains after the reaction goes complete. HCl is the limiting reactant, so the acid, it is all consumed.

Answer:

[tex]n=6\ to\ n=3[/tex]

Explanation:

From the question we are told that:

Wavelength [tex]\lambda=274 *10^{-9}m[/tex]

Bohr's constant [tex]R = 1.097 × 10^7 / m (or m−1)[/tex]

Helium atom [tex]z=2[/tex]

Generally the equation for Wavelength is mathematically given by

 [tex]\frac{1}{\lambda}=Rz^2(\frac{1}{nf^2}-\frac{1}{nf^2})[/tex]

 [tex]0.083=(\frac{1}{nf^2}-\frac{1}{nf^2})[/tex]

Therefore

The Range of n fall at

 [tex]n=6\ to\ n=3[/tex]

Answer:

89.35 hour

Explanation:

Recall :

Charge on 1 electron = 1.6 × 10^-19 C

1 mole contains = 6.023 × 10^23

Therefore, the charge on 1 mole of electron will be :

Charge per electron × 1 mole :

(1.6 × 10^-19) * (6.023 * 10^23) = 96500 C = 1 Farad

1 Farad = 96500 C

Using the formula :

Q = Current(I) * time(t)

Q = I*t

t = Q/I

Current, I = 0.3 A

t = 96500 / 0.3

t = 321666.66 second

t = 321666.66 / 3600 = 89.35 hour

Answer:

Close to the calculated endpoint of a titration - Partially open

At the beginning of a titration - Completely open

Filling the buret with titrant - Completely closed

Conditioning the buret with the titrant - Completely closed

Explanation:

'Titration' is depicted as the process under which the concentration of some substances in a solution is determined by adding measured amounts of some other substance until a rection is displayed to be complete.

As per the question, the stopcock would remain completely open when the process of titration starts. After the buret is successfully placed, the titrant is carefully put through the buret in the stopcock which is entirely closed. Thereafter, when the titrant and the buret are conditioned, the stopcock must remain closed for correct results. Then, when the process is near the estimated end-point and the solution begins to turn its color, the stopcock would be slightly open before the reading of the endpoint for adding the drops of titrant for final observation.

This question is incomplete, the complete question is;

A certain liquid X has a normal boiling point of 150.4 °C and a molar boiling point elevation constant kb is 0.60 °Ckgmol⁻¹.

A solution is prepared by dissolving some urea (NH22CO) in 750 g of X. This solution boils at 150.9 °C . Calculate the mass of urea that was dissolved. Round your answer to 3 significant digits.

Answer:

the mass of urea that was dissolved is 37.5 g

Explanation:

Given the data in the question;

normal boiling point of X; Tb⁰ = 150.4 °C

boiling point of solution Tb = 150.9 °C

Change in boiling point Δt = Tb - Tb⁰  = 150.9 °C - 150.4 °C = 0.5 °C

Kb = 0.6 °C.kg.mol⁻¹

V = 750 g

Now, we know that

Δt = Kb × molality

so

0.5 = 0.6 × molality

molality = 0.5 / 0.6

molality = 0.833

we know that molar mass of urea is 60 g/mol

so

molality = mass × 1000 / molar mass × volume( g )

we substitute

0.833 = ( mass × 1000 ) / ( 60 × 750 )

0.833 = ( mass × 1000 ) / 45000

0.833 × 45000 = mass × 1000

mass = ( 0.833 × 45000 ) / 1000

mass = 37485 / 1000

mass = 37.485 ≈ 37.5 g   { 3 significance figure }

Therefore, the mass of urea that was dissolved is 37.5 g

Answer:

1.6 x 10⁻²⁴ moles

Explanation:

We have 0.984 molecules of F₂. We know that 1 mol is equal to 6.022 x 10²³ molecules. Thus, we have a conversion factor: 1 mol/6.022 x 10²³ molecules

So, we multiply the molecules of F₂ by the conversion factor to calculate the moles:

0.984 molecules x  1 mol/6.022 x 10²³ molecules = 1.6 x 10⁻²⁴ moles

Answer: The product of the given reaction is [tex]HNO_{3}[/tex] and the solution at equilibrium will be acidic.

Explanation:

When two or more chemical substances react together then it forms new substances and these new substances are called products.

For example, [tex]3N_{2}O_{5} + 3H_{2}O \rightarrow 6HNO_{3}[/tex]

This shows that nitric acid [tex](HNO_{3})[/tex] is the product formed and it is an acidic substance.

Hence, the solution at equilibrium will be acidic in nature.

Thus, we can conclude that the product of the given reaction is [tex]HNO_{3}[/tex] and the solution at equilibrium will be acidic.

Answer:

all electrons of the atom

Answer:

none All have the same kinetic energy

Explanation:

Answer:

a little less than 109.5°

Explanation:

SCl2 has four regions of electron density around the central atom of the molecule. This implies that it has a tetrahedral electron domain geometry with an expected bond angle of 109.5° according to valence shell electron pair repulsion theory.

However, there are two lone pair of electrons on the central atom of the molecule which decreases the bond angle a little less than 109.5° owing to repulsion between electron pairs.

Answer:

6.7855 * 10^18

Explanation:

There are 2 moles in H2

Avagadro's number: 6.022E23

8.14E42*1/6.022E23 * 1/2

=6.7855 * 10^18

Answer:

the result for the following are (a) P is directly proportional to n

(b) V is directly proportional to T (c) P is directly proportional to T (d) T is inversly proportional to V (e) P is inversely proportional to V

The question is incomplete, the complete question is;

What functional group results when cyclopentanone reacts with ethylamine in the presence of trace acid? A) cyanohydrin B) semicarbazone C) imine D) enamine E) oxime

Answer:

imine

Explanation:

An imine is an unsaturated amine. An imine contains the carbon- nitrogen double bond.

Imines are obtained when a carbonyl compound is condensed with NH3 or an amine. The reaction involves several steps in its mechanism.

Since cyclopentanone is a ketone (carbonyl compound) and ethylamine is an amine,in the presence of trace acid, condensation of the two compounds occur to yield an imine

Answer:

Tin + silver trioxonitrate V -------->Tin IV nitrate + silver

Explanation:

The term word equation refers to an equation in which the reactants and products are written in words rather than chemical symbols.

Note than tin is above silver in the electrochemical series hence silver will be displaced by tin as follows;

Tin + silver trioxonitrate V -------->Tin IV nitrate + silver

Explanation:

In the formula of [tex]CaCl_2[/tex] we can see that there are 2mol Cl in 1 molecule of CaCl2. So, now we can do some math to find out how many mol of Cl there are in 1.9mol CaCl2!

[tex]1.9molCaCl_2*\frac{2molCl}{1molCaCl_2}[/tex]

So, there are 3.8mol Cl

Answer:

15 mL of the solute

Explanation:

From the question given above, the following data were obtained:

Solution = 50 mL

Solvent = 35 mL

Solute =?

Solution is simply defined as:

Solution = solute + solvent

With the above formula, we can easily obtain the solute in the solution as follow:

Solution = 50 mL

Solvent = 35 mL

Solute =?

Solution = solute + solvent.

50 = solute + 35

Collect like terms

50 – 35 = solute

15 = solute

Solute = 15 mL

Therefore, 15 mL of the solute is required.

Answer:

Theoretical yield is 138.4 g

Explanation:

In the first step we determine the reaction:

3Mg + N₂ → Mg₃N₂

Mass of reactant is 100 g. We assume the nitrogen is in excess, so we work with Mg. We convert mass to moles:

100 g . 1mol/ 24.3g = 4.11 moles of Mg.

Ratio is 3:1. 3 moles of Mg can produce 1 mol of nitride

Our 4.11 moles, may produce (4.11 . 1)/3 = 1.37 moles of Mg₃N₂

We convert mass to moles, to find the theoretical yield:

1.37 mol . 100.9 g/mol = 138.2 g

The formula that we can use to calculate energy released when a mass of liquid freezes is Grams liquid x mol/g x delta Hfusion.

Stoichiometry deals with the relationship between mass and moles or volume which can be used to make calculations involving chemical reactions. Most chemical calculations involving stoichiometry use the mole concept.

Hence, the formula used to obtain the energy released when a mass of liquid freezes is Grams liquid x mol/g x delta Hfusion.

Learn more about stoichiometry: https://brainly.com/question/9743981

Answer:

The best existing methods of control—artemisinin-based drug treatment and insect control with chemical sprays and treated bednets—can reduce the burden of disease substantially, and can even eliminate the disease in some regions,

hope this will help you more

Answer:

Alkaline earth metals or akali metals

The question is incomplete, the complete question is;

It takes 412. KJ/mol to break a carbon-hydrogen single bond. Calculate the maximum wavelength of light for which a carbon-hydrogen single bond could be broken by absorbing a single photon. Round your answer to significant digits.

Answer:

289 nm

Explanation:

The energy of the photon = 412 × 10^3/6.02 × 10^23 = 6.84 × 10^-19 J

From;

E = hc/λ

h= Plank's constant

c= speed of light

λ = wavelength

λ = hc/E

λ = 6.6 × 10^-34 × 3 × 10^8/6.84 × 10^-19

λ = 2.89 × 10^-7 m

λ = 289 nm

Answer:

Substrate

Explanation:

In biochemical sciences, a substrate is a substance that is acted upon by an enzyme to yield a product. Enzymes are known for catalyzing biochemical reactions. The substances that are usually worked with during this catalytic process are termed as SUBSTRATES.

Substrates, which are usually changed during the process, binds to the active site on the enzyme and form an enzyme-substrate complex.

According to this question, pyruvate is converted to lactate in a reaction that is catalyzed by the enzyme lactate dehydrogenase. This means that the compound on which the enzyme works, pyruvate, is called the SUBSTRATE.

Answer:2-chloro-1,3-dimethylcyclopentane

Explanation

Explanation:

Saturated fats are defined as the fat where fatty acid chains contain only single bonds.

For example, stearic acid, palmitic acid etc.

Unsaturated fats are defined as the fat where fatty acids contain one or more number of double bonds on the carbon atoms.

For example, oleic acid, palmitoleic acid etc.