chemical symbol for an atom of lithium​

Answer:

19 protons, 20 neutrons and 18 electrons.

Explanation:

The atomic number gives the number of protons 19

p = 19

The atomic mass is the sum of the protons and neutrons

p + n = 39   p = 19

put p into the equation and solve for n the neutrons.

19 + n = 39

Subtract 19 from both sides

19 − 19 + n = 39 − 19

n = 20

The number of electrons equals the number of protons in a neutral atom. The positive charge equals the negative charge. The negative charge is the number of electrons. This ion has a charge of +1. So solve for the negative charge.

− 19 + 1 = − 18

The negative charge is -18 so

e = 18

Sodium does not make up these proteins.

Explanation:

ionisation energy decrease down the group as the atomic radius increases. Nuclear charge increases. Number of shell increases so the electron will experience more shielding so it would be easier for the atom to loss electron.

Answer:

B

Explanation:

Its the sum of the protons and neutrons.

Explanation:

everything can be found in the picture

Answer:

How much energy would be produced from the reaction of 2.40 moles hydrogen with 3.95 moles chlorine?

[tex]H_2 + Cl_2 -> 2HCl , deltaH = -554 kJ[/tex]

Explanation:

Given,

2.40 moles hydrogen reacts with 3.95 moles chlorine.

From the balanced chemical equation,

1mol. of H2 reacts with 1mol. of Cl2

then,

2.40mol. of H2 reacts with ----?mol of Cl2

[tex]=>2.40 mol. H2 * \frac{1mol. Cl2}{1mol. H2} \\=2.40 mol. Cl2[/tex]

So, the remaining moles of Cl2 is in excess.

The limiting reagent is--- H2.

1mol. of H2 releases --- 554kJ of energy

then,

2.40mol of H2 releases ---- ?

[tex]=>2.40mol * \frac{554kJ}{1 mol.} \\=1329.6kJ[/tex]

Answer is: deltaH =-1329.6kJ

Answer:

Krypton

Explaination:

Element-Krypton

Symbol-Kr

Mass-83.8amu

charge-none

Answer:

283.5g

Explanation:

first u need to know the molar mass of hno3 which is 63.01

the g=1.5×3×63.01

g= 283.5

Answer:D. it lowers the amount of evergy needed for a reaction to occur.

Explanation:

a p e x

The concept Arrhenius equation is used here to determine the factor which increases the number of reactions. As the temperature increases, It increases the collisions that have enough energy to react. The correct option is B.

An equation which represents the relationship between the activation energy and rate of the reaction is known as the Arrhenius equation. According to this concept, lower the activation energy of a reaction, the higher its rate will be.

The equation is:

[tex]k = A . e^{-} ^{E_{a} } / RT[/tex]

k - Rate constant

A - Frequency factor

Eₐ - Activation energy

R - Gas constant

T - Temperature

When the temperature increases, the energy and speed of the molecules increases which in turn increases the number of effective collisions. If greater the value of frequency of collisions, then value of 'k' will be higher and greater is the number of reactions.

Thus the correct option is B.

To know more about rate of a reaction, visit;

https://brainly.com/question/30546888

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Answer: The molality of [tex]NaC_2H_3O_2[/tex] solution is 0.782 m

Explanation:

Molality is defined as the amount of solute expressed in the number of moles present per kilogram of solvent. The units of molarity are mol/kg. The formula used to calculate molality:

[tex]\text{Molality of solution}=\frac{\text{Moles of solute}}{\text{Mass of solvent (in kg)}}[/tex] .....(1)

Given values:

Moles of [tex]NaC_2H_3O_2[/tex] = 0.395 mol

Mass of solvent (water) = 0.505 kg

Putting values in equation 1, we get:

[tex]\text{Molality of }NaC_2H_3O_2=\frac{0.395mol}{0.505kg}\\\\\text{Molality of }NaC_2H_3O_2=0.782m[/tex]

Hence, the molality of [tex]NaC_2H_3O_2[/tex] solution is 0.782 m

Answer:

Coke

Explanation:

A solid fuel formed by heating coal in the absence of air is coke. Coke is black colored, tough porous substance. It is pure carbon.

The question is incomplete, the complete question is:

When heat is applied to 80 grams of CaCO3, it yields 39 grams of CaO Determine the percentage of the yield.

CaCO3→CaO + CO2

Answer: The % yield of the product is 87.05 %

Explanation:

The number of moles is defined as the ratio of the mass of a substance to its molar mass.

The equation used is:

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

We are given:

Given mass of [tex]CaCO_3[/tex] = 80 g

Molar mass of [tex]CaCO_3[/tex] = 100 g/mol

Putting values in equation 1, we get:

[tex]\text{Moles of }CaCO_3=\frac{80g}{100g/mol}=0.8mol[/tex]

For the given chemical reaction:

[tex]CaCO_3\rightarrow CaO+CO_2[/tex]

By stoichiometry of the reaction:

If 1 mole of [tex]CaCO_3[/tex] produces 1 mole of CaO

So, 0.8 moles of [tex]CaCO_3[/tex] will produce = [tex]\frac{1}{1}\times 0.8=0.8mol[/tex] of CaO

We know, molar mass of [tex]CaO[/tex] = 56 g/mol

Putting values in above equation, we get:

[tex]\text{Mass of CaO}=(0.8mol\times 56g/mol)=44.8g[/tex]

The percent yield of a reaction is calculated by using an equation:

[tex]\% \text{yield}=\frac{\text{Actual value}}{\text{Theoretical value}}\times 100[/tex] ......(2)

Given values:

Actual value of the product = 39 g

Theoretical value of the product = 44.8 g

Plugging values in equation 2:

[tex]\% \text{yield}=\frac{39 g}{44.8g}\times 100\\\\\% \text{yield}=87.05\%[/tex]

Hence, the % yield of the product is 87.05 %

Answer:

It is alkyne

Explanation:

Answer:

Verdadero.

Explanation:

¡Hola!

En este caso, dado que las propiedades periódicas nos hablan de un comportamiento específico sobre los elementos en la tabla periódica, resulta primeramente necesario recordar que la electornegatividad nos dice que tan fuerte es un elemento para atraer electrones de valencia de otros elementos.

De este modo, inferimos que es verdadero, ya que de hecho la electronegatividad nos define el tipo de enlace, basado en la diferencia de electronegatividades de los elementos enlazados, de acuerdo con la imagen adjunta.

Saludos!

Answer:

It's take 1 and a half hours

Explanation:

Ugbdunvisrtg

Answer:

C

Explanation:

In thermodynamics, a exothermic system looses heat to the surroundings while an endothermic system absorbs heat from the surroundings.

A system is a part the universe marked off by a specified boundary. The contents of the cup constitutes the system in this case.

The region of space outside the system is called the surroundings. Hence everything outside the cup constitutes the surroundings.

Answer:

gravity

Explanation:

Gravity is an example of the force of attraction between two objects that have mass.

Answer:

Endothermic reactions are reactions that require external energy, usually in the form of heat, for the reaction to proceed. In order to melt the ice cube, heat is required, so the process is endothermic. Endothermic reactionIn an endothermic reaction, the products are higher in energy than the reactants.

Explanation:

Answer:

put a salt into the beakers

3.3256 Liters

See the image I have shared to you above

Answer:

B. 7.2k

Explanation:

took the test ;)

Answer:

6 Watts

Explanation:

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

Current (I) = 0.05 A

Voltage (V) = 120 V

Power (P) =?

Electrical power is defined by the following equation

The power consumption while the TV is in standby can be obtained as follow:

Power (P) = Current (I) × Voltage (V)

P = IV

With the above formula, we can obtain the power consumption while the TV is in standby. This can be obtained as follow:

Current (I) = 0.05 A

Voltage (V) = 120 V

Power (P) =?

P = IV

P = 0.05 × 120

P = 6 Watts

Therefore, the power consumption while the TV is in standby is 6 Watts.

Answer:

504000 J

Explanation:

Applying,

Δq = cm(Δt)............. Equation 1

Where Δq = change in thermal energy, c = specific heat capacity of water,  m = mass of water, Δt = change in temperature.

From the question,

Given: m = 2 kg, Δt = 80-20 = 60°C

Constant; c = 4200 J/kg.°C

Substitute these values into equation 1

Δq = 2(4200)(60)

Δq = 504000 J

Hence the thermal energy is  504000 J

Answer:

mass (g) needed = 710.2 grams Na₂SO₄(s)

Explanation:

Needed is 2.5 Liters of 2.0M Na₂SO₄; formula wt Na₂SO₄ = 142.04g/mol.

mass (grams) of Na₂SO₄(s) = Molarity needed x Volume needed in Liters x Formula Wt of solute

mass (grams) of Na₂SO₄(s) = (2.5L)(2.0M)(142.04g/mol) = 710.2 grams Na₂SO₄(s)

Mixing: Transfer 710.4 grams Na₂SO₄ into mixing vessel and add water-solvent up to but not to exceed 2.5 Liters total volume. Mix until dissolved.

Gives 2.5 Liters of 2.0M Na₂SO₄(aq) solution.

Answer:

4 is chemical and 6 is a

Explanation:

hope this helps

Answer:

[tex]{ \tt{k _{c} = \frac{[Na_{2} O _{2} ]}{[Na] {}^{2} [O _{2} ]} }}[/tex]