Why do you need to use soap when you wash oil from your hands

If we add water to a concentrated acid, then the solution may boil very violently, splashing concentrated acid. If add acid to water, the solution that forms is very dilute and a small amount of heat is released.

When a strong acid is poured into water, it flows down the flask and mixes much better, so no boiling takes place. The addition of water to acid forms an extremely concentrated solution of acid initially. A large amount of heat is released and the solution may boil very violently, splashing concentrated acid out of the beaker and all this because the reaction is exothermic in nature.

The reason this takes place is due to a large amount of energy liberated in the hydration reaction of concentrated ions. Therefore, we add acid to water dropwise for the dilution with constant stirring and not water to acid directly.

If we add water to acid, then an exothermic reaction occurs and the solution may boil very violently. To form the dilute solution of any strong acid, you should add acid to water and the small amount of heat released is not sufficient to vaporize and spatter it.

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Answer: The percent yield of the reaction is 77.0 %

Explanation:

[tex]2Pb+O_2\rightarrow 2PbO[/tex]

[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}[/tex]

[tex]\text{Number of moles of lead}=\frac{451.4g}{207.2g/mol}=2.18moles[/tex]

[tex]\text{Number of moles of lead oxide}=\frac{374.7g}{223.2g/mol}=1.68moles[/tex]

According to stoichiometry:

2 moles of [tex]Pb[/tex] produces = 2 moles of [tex]PbO_2[/tex]

2.18 moles of [tex]Pb[/tex] is produced by=[tex]\frac{2}{2}\times 2.18=2.18moles[/tex] of [tex]PbO_2[/tex]

Mass of [tex]PbO_2[/tex] =[tex]moles\times {\text {Molar mass}}=2.18\times 223.2g/mol=486.6[/tex]

percent yield =[tex]\frac{374.7g}{486.6g}\times 100=77.0\%[/tex]

Answer:

(3) sorry if I'm wrong

7.  (1-fertilization [sorry if wrong again]

8. (4-mitosis

Explanation:

I'm learning about this right now...Sorry if I'm wrong but I'm pretty sure they're right! Hope this helps tho! if I'm right maybe mark me brainliest?

Answer:

m*s⁻¹.

Explanation:

Hello!

In this case, since the frequency measures how repetitive an event is per unit of time, for instance the laps a car drives every 5 minutes or something similar, we can infer it has units of event/time; in such a way, the unit m*s⁻¹ is not a proper unit of frequency because it is a proper unit of velocity which is the distance traveled per unit of time.

In such a way, Hz (hertz), s⁻¹ and 1/s are possible ways frequency can be represented.

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Answer:

The velocity would be if m was meters +1200

Explanation:

im smart

Answer:

D.All three graph lines peak over the same few weeks of winter.

Explanation:

took the test

This follows a simple conversion technique. Basically what the question is trying to say here is to convert 29.1 inHg to mmHg. 1 inHg is equal to 25.4 mmHg so 29.1 inHg would be equal to [tex]25.4 * 29.1[/tex] which when evaluated turns out to be: [tex]739.14[/tex]. :D

The pressure will be 739.14 mm Hg.

The SI unit measuring pressure would be the pascal, which measures the force of each unit area of the surface.

Calculation of pressure

It is known that 1inHg = 25.4 mm Hg.

Hence, the pressure = 25.4 × 29.1 = 739.14 mm Hg

Therefore, the pressure will be 739.14 mm Hg.

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Answer:

False

Explanation:

They’re used cause they’re generally harder than pure metals

Alloys are used much more than pure metals because they are generally stronger and less likely to react with air or water...

So I would say false

Answer:

Zn + 2HCl -----> ZnCl₂ + H₂

Explanation:

The balanced chemical equation for Zn with hydrogen is Zn + 2HCl ---> ZnCl₂+ H₂.

What is balanced chemical equation?

A balanced chemical equation is one in which number of reactant is equal to number of products. When Zinc reacts with hydrogen it will form zinc chloride and hydrogen gas.

Here, 1 molecules of hydrochloric acid are participating in the process, and 1 molecules of hydrogen are being created.

Therefore, The balanced chemical equation for Zn with hydrogen is Zn + 2HCl ---> ZnCl₂+ H₂.

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Answer:

632.7 secs

Explanation:

Equation of the reaction:

Tl^3+ + 3e ------> Tl

If 1F = 96500 C

Q= It

Where;

I= current

t= time

3× 96500 C deposited 204 g of Tl

0.868 × t deposited 0.387 g of Tl

3 × 96500 × 0.387 = 204 × 0.868 × t

t= 3 × 96500 × 0.387/ 204 × 0.868

t= 632.7 secs

The time required for a constant current of 0.868 A to deposit 0.387 g of Tl(III) as Tl(s) is 2689 s

We'll begin by calculating the quantity of electricity needed to deposit 0.387 g of Ti

Ti³⁺ + 3e —> Ti

Recall:

1 mole of Ti = 48 g

1 electron (e) = 96500 C

Thus,

3 electrons = 3 × 96500 = 289500 C

From the balanced equation above,

48 g of Ti was deposited by 289500 C of electricity.

Therefore,

0.387 g of Ti will be deposited by = (0.387 × 289500) / 48 = 2334.09375 C of electricity

Quantity of electricity (Q) = 2334.09375 C

Current (I) = 0.868 A

t = Q / I

t = 2334.09375 / 0.868

Therefore, the time required for the reaction is 2689 s

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Answer:

349.22°C

Explanation:

Let the final temperature of the two pieces of metal be x.

Now, the warmer metal which is C u reduces from 475°C to x. Thus Δt for C u is; Δt1 = 475 - x.

The cooler metal Cr increases in temperature from 265°C to x. Thus, it's change in temperature is Δt for Cr is; Δt2 = x - 265.

Now from conservation of energy, the amount of energy leaving the C u metal is equal to the amount of energy entering the Cr metal.

Thus;

q_lost = q_gain

Where;

q_lost = m1•c1•Δt1

q_gained = m2•c2•Δt2

Now, c1 & c2 are the specific heat capacity of C u and Cr respectively.

From online tables, c1 = 0.385 J/g°C and c2 = 0.46 J/g°C

We are given;

m1 = 12g and m2 = 15g

Thus;

12 × 0.385 × (475 - x) = 15 × 0.46 × (x - 265)

2194.5 - 4.62x = 6.9x - 1828.5

6.9x + 4.62x = 2194.5 + 1828.5

11.52x = 4023

x = 4023/11.52

x = 349.22°C

Answer:

The answer is "[tex]37.45364 \ g[/tex]"

Explanation:

Equation:

[tex]2AgNO_3 (aq) + Na_2CO_3 (aq) \longrightarrow Ag_2CO_3 (s) + 2NaNO_3 (aq)[/tex]

Calculating  the mol of  [tex]AgNO_3[/tex]:

[tex]\to V = 40.0 mL\\\\[/tex]

       [tex]= 40.0 \times 10^{-2} \ L \\\\[/tex]

[tex]\to n = Molarity \times Volume \\\\[/tex]

       [tex]= 0.679 \times 40.0 \times 10^{-2}\\\\= 27.16 \times 10^{-2} \ mol[/tex]

mol of [tex]Ag_2CO_3= \frac{1}{2} \times n\\\\[/tex]

                         [tex]= \frac{1}{2} \times 27.16 \times 10^{-2}\\\\= 13.58 \times 10^{-2}\\\\[/tex]

Calculating the molar mass of [tex]Ag_2CO_3[/tex],:

[tex]= 2\times MM(Ag) + 1 \times MM(C) + 3 \times MM(O)\\\\= 2 \times 107.9 + 1 \times 12.01 + 3 \times 16.0\\\\= 275.81 \ \frac{g}{mol}[/tex]

Calculating the mass of [tex]Ag_2CO_3[/tex],

[tex]m = mol \times molar \ mass[/tex]

   [tex]= 13.38 \times 10^{-2}\ mol \times 2.758 \times 10^2 \ \frac{g}{mol}\\\\= 37.45364 \ g[/tex]

Answer:

Carbohydrates

Explanation:

Living things use carbohydrates as their main source of energy. The breakdown of sugars, such as glucose, supplies immediate energy for cell activities. Plants, some animals, and other organisms also use carbohydrates for structural purposes.

Answer:

Alkali Metals

Explanation:

They're the most reactive elements in group one.

Answer:

This question is incomplete

Explanation:

However, when the carboxylic acids and esters put together are obtained, the procedure below can be followed in drawing and naming them.

For carboxylic acid,

1) it should be noted that the functional group here is -COOH which is drawn as -C = OH

      |

     OH

2) The carbon of the functional group is included among the carbon to be counted when naming the structure. For example, the compound below is propanoic acid.

CH₃CH₂COOH - As you can see that there are 3 carbons linked chain there.

3) As can be seen in (2) above, the suffix "oic" is used to name carboxylic acids

4) The carbon chain here is saturated (meaning there is no double or triple bond within the carbon chain)

Example of a structure of carboxylic acid is

H₃C - CH₂ - CH₂ - C = OH

                              |

                             OH

The structure above is a butanoic acid

For ester

1)The functional group here is -COO- . which can be drawn as

- C = O

   |

  O -

(meaning one oxygen atom is double bonded to the carbon and the other oxygen atom is bonded to another carbon chain)

2) The alkyl group attached to the oxygen atom is first of all mentioned before the carbon chain attached from the left is mentioned. For example, CH₃CH₂CH₂COOCH₂CH₃ is ethyl butanoate

3) As seen from (2) above, the suffix "oate" is used to end the name of esters

4) As also seen from (2) above, the carbon of the functional group is also included while counting the carbon chain of the parent name (butanoate).

5) The carbon chains here are also saturated.

Example of this ester is

CH₃CH₂C = O

              |

             O - CH₂CH₃

The name of this compound is ethyl propanoate

Answer:

During the reaction, chemical bonds break in the reactants and new chemical bonds form in the products.

Answer:

d. Atoms are rearranged.

Explanation:

Answer:

Explanation:

1. Cornstarch and water - decantation

2. Iron and sulfur

3. Rice grains and stones - sieving

4. Pebbles and soil - decantation

5. Muddy water - decantation

6. Ground pepper and water - decantation

7. Flour and coarsely ground corn - sieving

8. Needles in a box of beads - using a magnet

9. Sesame seeds in soy sauce -

10. Pebbles and iron nails - using a magnet

11. Fine sand from rocks - sieving

12. Sand from water - filtration

13. Gravel and sand - sieving

14. Salt and iron filings - sieving

15. Pins from assorted buttons - using a magnet

16. Coconut oil from coconut milk - filtration

17. Sand and pebbles - sieving

18. Pasta from water - sieving

19. Sand and thumb tacks - using a magnet

20. Salt solution - filtration

Answer:

liquid

Explanation:

correct answer hope it helps

Answer: Spun yarn is made by twisting staple fibers together

To make a cohesive thread Or “single”. Twisting fibers, into yarn in the process called spinning can be dated back to the upper Paleolithic. Yarn spinning was one of the first processes to be industrialized.

Explanation:

Answer:

The maximum possible yield strength for a single crystal is 70 MPa.

Explanation:

To find the maximum possible yield strength for a single crystal we need to use the following equation:

[tex]\sigma_{y} = \frac{\tau_{CRSS}}{m_{max}}[/tex]

Where:

[tex]m_{max}[/tex] is the maximum value for Schmid factor

[tex]\tau_{CRSS}[/tex] is the critical resolved shear stress = 35 MPa

[tex] \sigma_{y}[/tex] is the yield strength =?    

The Schmid factor is given by:

[tex]m = cos(\phi)cos(\lambda)[/tex]

And its maximum value is obtained when λ = 45° and Φ = 45°, so:

[tex] m = cos(45)cos(45) = 0.5 [/tex]

Finally, the maximum possible yield strength is:

[tex]\sigma_{y} = \frac{\tau_{CRSS}}{m_{max}} = \frac{35 MPa}{0.5} = 70 MPa[/tex]

Therefore, the maximum possible yield strength for a single crystal is 70 MPa.

I hope it helps you!                                                                                  

Answer:

The flask has to be closed during the hydrochloric acid and sodium carbonate reaction as the resultant gas got trapped inside the closed flask.

Explanation:

The hydrochloric acid and sodium carbonate reaction was exothermic that caused the pressure to decrease. The flask has to be closed during the hydrochloric acid and sodium carbonate reaction as the resultant gas got trapped inside the closed flask.

In exothermic reactions, energy is produced in the form of heat or light.

Answer:

B) . six electrons in the triple bond of diatomic nitrogen

Explanation:

The three line in this Lewis dot structure represents the six electrons in the triple bond of diatomic nitrogen.

Nitrogen is made up of 7 electrons with 5 valence ones.

 A lewis structure is made up of the symbol of the element surrounded by dot to represent the valence electrons.

  In this nitrogen molecule, both species share  6 electrons. This makes each nitrogen atom isoelectronic with neon.

Answer:

one example of chemical weathering is when carbon dioxide mixes with water.

Explanation:

when dioxide mixes with water it creates carbonation.

1: FALSE The physical properties of metals include shininess, malleability, ductility, and conductivity.

2: FALSE Neutrons are the particles in an atom that have a neutral charge. They aren't positive like protons. They aren't negative like electrons.

3: TRUE Dmitri Ivanovich Mendeleev was a Russian chemist and inventor. He is best remembered for formulating the Periodic Law and creating a farsighted version of the periodic table of elements. He is also known as the "father of the periodic table"

Answer:

1.T, 2.F., 3.T

Explanation:

2 is false because electrons have a negative charge neutrons have no charge

Answer:

D. Supported by observations

Explanation:

Because theories change over time, they both need to be proven, they do not go off of consensus, but they do need to be supported by observations.

HOPE IT HELPS❣️

Answer:

I hope you do well on the test good luck

Explanation:

Answer:

[tex]m_{CO2}=8.33gCO2[/tex]

Explanation:

Hello.

In this case, since the chemical reaction is:

[tex]C_7H_5N_3O_6(s)+\frac{21}{4} O2(g)\rightarrow 7CO_2(g)+\frac{3}{2} N_2(g)+\frac{5}{2} H_2O(l)[/tex]

Thus, since we have the initial moles of TNT:

[tex]n_{TNT}=25.7g*\frac{1mol}{227.13g} =0.113mol[/tex]

And the initial moles of oxygen given the ideal gas equation:

[tex]n_{O_2}=\frac{6.93atm*0.5L}{0.082\frac{atm*L}{mol*K}*298K}=0.142molO_2[/tex]

Given the 1:7 mole ratio between TNT and carbon dioxide and the 21/4:7 mole ratio between oxygen and carbon dioxide, we compute the yielded moles by each reactant:

[tex]n_{CO_2}^{by\ TNT}=0.113molTNT*\frac{7molCO_2}{1molTNT}=0.791molCO_2\\\\ n_{CO_2}^{by\ O_2}=0.142molO_2*\frac{7molCO_2}{21/4molO_2}=0.189molCO_2[/tex]

Thus, since oxygen yields less moles of carbon dioxide than TNT, we infer it is the limiting reactant, therefore, the produced mass of carbon dioxide is:

[tex]m_{CO2}=0.189molCO2*\frac{44.01gCO2}{1molCO2}\\\\m_{CO2}=8.33gCO2[/tex]

Best regards!