Tear gas products are less effective against violent attackers. true or false

Which of the following pieces of laboratory glassware should be used to most accurately measure out a 25.00 ml sample of a solut

wel

Answer:

The correct answer is 25 mL graduated cylinder (it should be used in all the cases)

Explanation:

In order to measure 25.00 ml sample of a solution it should be used a 25 mL graduated cylinder, as it is previously and properly calibrated. The other laboratory glassware, beaker and erlenmeyer, have graduations which are approximate, so they are used when exact volumes are not needed.

ii) graduated cylinder has the least uncertainly. It is more accurate than a beaker or erlenmeyer (to within 1%)

iii) A 25 mL graduated cylinder should be used because it is the most accurate lab glassware (between those were mentioned: beaker, erlenmeyer).

6 0

3 years ago

Which of the following characteristics do all unicellular organisms share?

Serhud [2]

Unicellular organisms...

Contain a single cell in their body

Do not contain membrane bound organelles

Use simple diffusion as a transport mechanism

All cellular processes are carried out by the single cell

Only visible under the microscope

Injury in the cell leads to the death of the organism

Asexually reproduce by binary fission

Sexually reproduce by conjugation

Lifespan is comparatively short

3 0

3 years ago

Determine ΔH for the reaction CaCO3 → CaO + CO2 given these data: 2 Ca + 2 C + 3 O2 → 2 CaCO3 ΔH = −2,414 kJ C + O2 → CO2 ΔH = −

kicyunya [14]

Answer:

The ΔH for the reaction is -456.5 KJ

Explanation:

Here we want to determine ΔH for the reaction;

Mathematically;

ΔH = ΔH(product) - ΔH(reactant)

In the case of the first reaction;

ΔH = ΔH(CaO) + ΔH(CO2) - ΔH(CaCO3) ...........................(*)

From the other reactions, we can get the respective ΔH for the individual molecule in the reaction

In second reaction;

Kindly note that for elements, molecule of gases, ΔH = 0

What this means is that throughout the solution;

ΔH(Ca) = 0 KJ

ΔH(O2) = 0 KJ

ΔH(C) = 0 KJ

Thus, in writing the equation for the subsequent chemical reactions, we shall need to write and equate the overall ΔH for the reaction to that of the product alone

So in the second reaction

ΔH = 2ΔH(CaCO3)

Thus;

-2414/2 = ΔH(CaCO3)

ΔH(CaCO3) = -1,207 KJ

Moving to the third reaction, we have;

ΔH = ΔH(CO2)

Hence ΔH(CO2) = -393.5 KJ

For the last reaction;

ΔH = ΔH(CaO)

Hence ΔH(CaO) = -1270 KJ

Going back to equation *

ΔH = ΔH(CaO) + ΔH(CO2) - ΔH(CaCO3)

Using the values of the ΔH of the respective molecules given above,

ΔH = -1270 + (-393.5) - (-1207)

ΔH = -456.5 KJ

8 0

3 years ago

The electronegativity values of fluorine, oxygen, and hydrogen are compared in the table. Comparison of Electronegativity Elemen

Dvinal [7]

The hydrogen bonding in H₂O is stronger than that of HF

Explanation:

Hydrogen bonds are special dipole-dipole attraction in which electrostatic attraction is established between hydrogen atom of one molecule and the electronegative atom of a neighboring molecule.

The strength of hydrogen bonds depends on the how electronegative an atom is.
Electronegativity refers to the tendency of an atom to gain electrons.
The higher the value, the higher the tendency.
This why oxygen with a higher electronegativity will form a stronger hydrogen bond with hydrogen compared to fluorine.

Learn more:

hydrogen bond brainly.com/question/12408823

#learnwithBrainly

4 0

3 years ago

In an experiment, hydrochloric acid reacted with different volumes of sodium thiosulfate in water. A yellow precipitate was form

iris [78.8K]

Answer:

I think that the trend that would be seen in the time column of the data table would be that the number of seconds would increase. I know this because for each flask, the concentration of sodium thiosulfate decreases, since less of it is being mixed with more water. Also, when the concentration of a substance decreases, then the reaction rate also decreases, as there will be fewer collisions with sulfuric acid if there are fewer moles of sodium thiosulfate. When there are fewer collisions in a reaction, the reaction itself will take longer, and so when the sodium thiosulfate is diluted, the reaction takes more time.

Explanation:

<em>I verify this is correct. </em>

6 0

3 years ago