someone help plz!

what is a Hydrogel?​

Answer:

Formula and structure: The chemical formula of calcium chloride is CaCl2, and its molar mass is 110.983 g/mol. It is an ionic compound consisting of the calcium cation (Ca2+) and two chlorine anions (Cl-). The bivalent calcium metal forms an ionic bond with two chlorine atoms, as shown below.

Based on the ionic nature of calcium chloride,  the chemical symbols of the particles found in the calcium chloride crystal is Ca²⁺ and Cl⁻.

Ionic compounds are compounds which are composed of ions.

Calcium chloride is an ionic compound composed of the ions, calcium ions and chloride ions.

The chemical formula of calcium chloride is CaCl2, and its molar mass is 110.983 g/mol.

The symbol for  calcium ion is Ca²⁺

The symbol for chloride ion is Cl⁻.

Therefore, the chemical symbols of the particles found in the calcium chloride crystal is Ca²⁺ and Cl⁻.

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Answer: 61.98 is correct

Explanation:

Molar mass of calcium nitrate is 164  g/mole which is obtained by adding atomic weights of constituent elements.

Molar mass of a compound or a molecule is defined as the mass of the elements which are present in it.The molar mass is considered to be a bulk quantity not a molecular quantity. It is often an average of the of the masses at many instances.

The molecular mass and formula mass are used as synonym for the molar mass.It does not depend on the amount of substance which is present in the sample.It has units of gram/mole.

Molar masses of an element are given as relative atomic masses while that of compounds is the sum of relative atomic masses which are present in the compound.

Molar mass of calcium nitrate =40+[14+(16×3)]×2=164 g/mole.

Thus, the molar mass of calcium nitrate is 164 g/mole.

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Answer: A reaction which occurs when equivalent quantities of H" (or [tex]H_{3}O^{+}[/tex]) and OH" are mixed is a neutralization reaction.

Explanation:

When acid and base chemically combine together to form sat and water then it is know as neutralization reaction.

An acidic substance gives hydrogen ions [tex](H^{+})[/tex] on dissociation and a basic substance gives hydroxide ions [tex](OH^{-})[/tex] on dissociation.

For example, [tex]H^{+} + OH^{-} \rightarrow H_{2}O[/tex] is a neutralization reaction where an acid and base are mixed together to form water.

No salt is formed as because here the reactants are not present as compounds.

In a hydrolysis reaction, water molecule(s) is added to the reactant molecules.

For example, [tex]CH_{3}COOCH_{3} + H_2O \rightarrow CH_{3}COOH + CH_{3}OH[/tex]

Oxidation is the process of addition of oxygen to a molecule and removal of hydrogen.

Reduction is the process of addition of hydrogen in a compound and the removal of oxygen atom.

Therefore, we can conclude that reaction which occurs when equivalent quantities of H" (or [tex]H_{3}O^{+}[/tex]) and OH" are mixed is a neutralization reaction.

Answer:   B. Magnesium, strontium, radium, barium

Explanation:

Elements are distributed in groups and periods in a periodic table.

Elements that belong to same groups will show similar chemical properties because they have same number of valence electrons.

Magnesium (Mg) , Strontium (Sr) , Radium (Ra) and Barium (Ba) are elements which belong to Group 2. They have 12, 38, 88 and 56 electrons respectively and contain 2 valence electrons each and need one electron to complete their octet.

The chemical reactivity of elements is governed by the valence electrons present in the element and thus they are alike in physical and chemical properties.

Answer:

each compound or molecule is indicated in subscript next to the compound by an abbreviation in parentheses. For example, a compound in the gas state would be indicated by (g), solid (s), liquid (l), and aqueous (aq).

Explanation:

Answer:

Your answer is B

Boron

Good luck

Explanation:

Answer: 4.5

Explanation:

Answer:

I think hydrogen because Hydrogen combined with one atom with oxygen and in hydrogen peroxide. It has two atoms of hydrogen and 2 atoms of oxygen. Therfore it should be a compound.

Answer:

There are chemical cross-links between the two strands in DNA, formed by pairs of bases. They always pair up in a particular way, called complementary base pairing: thymine pairs with adenine (T–A) guanine pairs with cytosine (G–C)

Explanation:

Hope it helps u

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Answer:

Lungs.

Explanation:

They bring the blood throughout the body, to help it function properly

Answer:

See explanation

Explanation:

The valence shell electron pair repulsion theory states that; the number of electron pairs present on the valence shell of the central atom in a molecule is the final determinant of shape of the molecule.

Based on this theory, the electron domain geometry of a molecule having 4 outer atoms and 1 lone pairs on the central atom should be based on a trigonal bipyramid. The molecular geometry of this molecule is see saw with a bond angle of <90 degrees(axial) and <120 degrees(equatorial).

Answer:

2H+(aq) + CaCO3(s) → Ca2+(aq) + H2O(l) +. CO2(g). [ 2]. Award [1] for correct reactants and products. Award [1] if the ... Exercises. 1 Reaction gives off a gas: change in volume could be measured.

Answer: 7.98 grams of [tex]Fe_2O_3[/tex] are produced if 10.7 grams of [tex]Fe(OH)_3[/tex] are reacted.

Explanation:

To calculate the number of moles, we use the equation:

[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}[/tex]      .....(1)  

Putting values in equation 1, we get:

[tex]\text{Moles of} Fe(OH)_3=\frac{10.7g}{106.87g/mol}=0.100mol[/tex]  

The chemical equation for the reaction is

[tex]2Fe(OH)_3\rightarrow Fe_2O_3+3H_2O[/tex]

By Stoichiometry of the reaction:

2 moles of [tex]Fe(OH)_3[/tex] produce = 1 mole of [tex]Fe_2O_3[/tex]

So, 0.100 moles of [tex]Fe(OH)_3[/tex] produce= [tex]\frac{1}{2}\times 0.100=0.05mol[/tex] of [tex]Fe_2O_3[/tex]  

Mass of [tex]Fe_2O_3[/tex] =[tex]moles\times {\text{Molar Mass}}=0.05mol\times 159.69g/mol=7.98g[/tex]  

Hence 7.98 grams of [tex]Fe_2O_3[/tex] are produced if 10.7 grams of [tex]Fe(OH)_3[/tex] are reacted.

Answer:

The number of moles represented by 21.7 L is 0.96875 moles

Explanation:

The volume occupied by one mole of a gas which consists of (approximately) 6.022 × 10²³ elementary at STP is 22.4 L. The volume is known as the molar volume of gas

Therefore, the number of moles, 'n', present in 21.7 L of gas at STP is given as follows;

The number of moles represented by 22.4 L = 1 mole

∴ The number of moles represented by 21.7 L = 1 mole/22.4 L × 21.7 L = 0.96875 moles

The number of moles represented by 21.7 L = 0.96875 moles.

Answer:

C

Explanation:

Answer:

D)

Explanation:

On land, volcanoes form when one tectonic plate moves under another. Usually a thin, heavy oceanic plate subducts, or moves under, a thicker continental plate. When this happens, the ocean plate sinks into the mantle.

Answer:

Thermal Energy

Explanation:

The thermal energy of an object increases as the temperature increases, causing atoms and molecules to move faster. When the temperature decreases, the thermal energy decreases, causing atoms and molecules to move slower. Another term for thermal energy is heat energy.

Answer:

10

Explanation:

Answer:

All of the energy from the Sun that reaches the Earth arrives as solar radiation, part of a large collection of energy called the electromagnetic radiation spectrum. Solar radiation includes visible light, ultraviolet light, infrared, radio waves, X-rays, and gamma rays. Radiation is one way to transfer heat.

Answer:

number one and and the third one but im not sure srry if i got it wrong

Answer:

ph=2

Explanation:

Answer:

28.93 g/mol

Explanation:

This is an extension of Graham's Law of Effusion where [tex]\frac{R1}{R2} = \sqrt{\frac{M2}{M1} } = \frac{t2}{t1}[/tex]

We're only talking about molar mass and time (t) here so we'll just concentrate on [tex]\sqrt{\frac{M2}{M1} } = \frac{t2}{t1}[/tex]. Notice how the molar mass and time are on the same position, recall effusion is when gas escapes from a container through a small hole. The time it takes it to leave depends on the molar mass. If the gas is heavy, like Xe, it would take a longer time (4.83 minutes). If it was light it would leave in less time, that gives us somewhat an idea what our element could be, we know that it's atleast an element before Xenon.

Let's plug everything in and solve for M2. I chose M2 to be the unknown here because it's easier to have it basically as a whole number already.

[tex]\sqrt{\frac{M2}{131} } = \frac{2.29}{4.83}[/tex]

The square root is easier to deal with if you take it out in the first step, so let's remove it by squaring each side by 2, the opposite of square root essentially.

[tex](\sqrt{\frac{M2}{131} } )^2= (\frac{2.29}{4.83})^2[/tex]

[tex]{\frac{M2}{131} } = (0.47)^2[/tex]

[tex]{\frac{M2}{131} } = 0.22[/tex]

M2= 0.22 x 131

M2= 28.93 g/mol

Answer:

1. Graphite rod (cathode)

2. Positive terminal

3. Solid zinc layer (anode)

4. Paste (reduction takes place here)

5. Negative terminal

Explanation:

This was the only thing i could find on it. hope this helps.

Answer:

Explanation:

• Label all parts.

1. Cathode or Graphite Rod

2. Positive terminal  

3. Anode or Solid Zinc layer  

4. Electrolyte Paste (reduction takes place here)

5. Negative Terminal (maybe this could also be the Zinc casing)  

• Label the cathode and the anode, including the charges on each.

The anode is the zinc layer is negatively charged and the cathode is the graphite rod is positively charged.  

• Show the flow of electrons.

The zinc casing is oxidized and the electrons flow along the zinc layer, into the negative terminal, and then out the negative terminal. The electrons move from the wire to the graphite rod. Then from the rod the electrons move to the paste, then the past goes through reduction. The anode gets a negative charge as electrons are released, and the cathode gets a positive charge as the electrons, which are negatively charged, are consumed.

• Explain how the cell works. Include the oxidation and reduction half-reactions in your explanation.

Alkaline dry cells use spontaneous oxidation-reduction reactions to convert chemical energy to electrical energy. According to the lesson ‘’Half-reactions are combined in a small casing, but still separated into half-cells.’’

Answer:

An allotrope is one way that atoms can be arranged in a solid. An isotope is one way that protons and neutrons can form the same atomic element.

Answer: The percent by mass concentration is 33.3 %

Explanation:

Mass percent is the ratio of mass of solute to the mass of solution in terms of percentage.

mass of solute = 50 g

mass of solution = [tex]{\text {density of solution}}\times {\text {volume of solution}}=1.5g/ml\times 1000ml=1500g[/tex]

Mass percentage = [tex]\frac{50g}{1500g}\times 100\%=33.3\%[/tex]

Thus percent by mass concentration of 1000 ml of a solution (d=1.5 g/ml) that contains 50 g of solute in it is 33.3 %

Answer:

2 moles H

2

Explanation:

Your tool of choice here will be the mole ratio that exists between zinc metal,  

Zn

, and hydrochloric acid,  

:HCl

, in the balanced chemical equation.

Zn

(s]

+

2

HCl

(aq]

→

ZnCl

2(aq]

+

H

2(g]

↑

⏐

You're dealing with a single replacement reaction in which zinc displaces the hydrogen from hydrochloric acid. The products of the reaction are aqueous zinc chloride and hydrogen gas.

Now, as you can see from the balance chemical equation, a  

1

:

2

mole ratio exists between the two reactants.

This tells you that in order for the reaction to take place, you need to have twice as many moles of hydrochloric acid as you do of zinc metal.

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At the same time, you have a  

2

:

1

mole ratio between hydrochloric acid and hydrogen gas.

This means that the reaction will always produce half as many moles of hydrogen gas as you have moles of hydrochloric acid.

Since you know that  

4

moles of hydrochloric acid are taking part in the reaction, and assuming that you have enough zinc metal so that it doesn't act as a limiting reagent, you can say that the reaction will produce

4

moles HCl

⋅

1 mole H

2

2

moles HCl

=

2 moles H

2

Explanation:

Answer:

27J/Kmol

Explanation:

Heat = number of moles times the Moeller heat capacity chimes the change in temperature.

^ Q = nC△T

^ C = Q/ n△T = +53J / (1mol) (299.5K - 297.5K)

^ = 26.5 (rounded to 27)