What is the total number of electrons in an atom of an element with an atomic number of 18 and a mass number
of 402
a. 58
c. 22
b. 18
d. 40

Heat required : 4.8 kJ

The heat to change the phase can be formulated :

Q = mLf (melting/freezing)

Q = mLv (vaporization/condensation)

Lf=latent heat of fusion

Lv=latent heat of vaporization

The heat needed to raise the temperature

Q = m . c . Δt

1. heat to raise temperature from -20 °C to 0 °C

[tex]\tt Q=10\times 2.09\times (0-(-20)=418~J[/tex]

2. phase change(ice to water)

[tex]\tt Q=10\times 333=3330~J[/tex]

3. heat to raise temperature from 0 °C to 25 °C

[tex]\tt Q=10\times 4.18\times (25-0)=1045~J[/tex]

[tex]\tt Q~tot=418+3330+1045=4793~J\rightarrow rounding~and~2~sig~figs=4.8~kJ[/tex]

Answer:

179.87 g/mol

Explanation:

First you need to determine the number of each elements in the molecule.  This information comes from the molecular formula.  

Ze(NO3)2 tells us that there is 1 Ze atom and 2 NO3 anions per molecule.  each NO3 anion will have 1 nitrogen and 3 oxygens.  Due to that, one molecule of Ze(NO3)2 will have 1 atom of Ze, 2 atoms of nitrogen (N), and 6 atoms of oxygen (O).

Next you need to add all of the individual atom's molar masses to get the over all molar masses.  The molar masses of each element is in the question but it can also be found on the periodic table.

molar mass of Ze(NO3)2 = 55.85g/mol + (14.01g/mol*2) + (16.00g/mol*6)

molar mass of Ze(NO3)2 = 179.87 g/mol

I hope this helps.

Answer:

Explanation:

true it is 1064 c

Answer:

true

Explanation:

it's 1064º C

Answer:

1. balanced

2.unbalanced

3.unbalabced

4.balanced

Answer:

Explanation:

I'm not going to lie, I think I did this completely wrong. But you can use this. I was completely lost on this assignment.

Answer:

I believe this is the answer

Explanation:

Answer:

The specific heat of magnesium is 1.02 J/g.K

Explanation:

To calculate the energy involved in the heating of the metal (magnesium), we use the following expression:

energy = mass x Cp x ΔT

We have the following data:

mass = 2.00 kg x 1000 g/1.00 kg = 2000 g

energy = 8160 J

ΔT = 4 K

Thus, we can calculate the specific heat of magnesium (Cp) in J/g.K as follows:

⇒ Cp = energy/(mass x ΔT) = 8160 J/(2000 g x 4K) = 1.02 J/g.K

Grams of Ca(NO₃)₂ produced : 0.985 g

A reaction coefficient is a number in the chemical formula of a substance involved in the reaction equation. The reaction coefficient is useful for equalizing reagents and products.

Reaction

CaCl₂ + 2AgNO₃ → 2AgCl + Ca(NO₃)₂

MW AgNO₃ : 107.9+14+3.16=169.9

mol AgNO₃ :

[tex]\tt \dfrac{2}{169.9}=0.012[/tex]

mol ratio Ca(NO₃)₂ : AgNO₃ = 1 : 2, so mol Ca(NO₃)₂ :

[tex]\tt \dfrac{1}{2}\times 0.012=0.006[/tex]

MW Ca(NO₃)₂ : 40.1+2.14+6.16=164.1 g/mol

mass Ca(NO₃)₂ :

[tex]\tt 0.006\times 164.1=0.985[/tex]

Answer:

D.

Explanation:

Emerging infectious disease

Answer:

d

Explanation:

emerging infectious disease

Answer:

13598 J

Explanation:

Q = m × c × ∆T

Where;

Q = amount of energy (J)

m = mass (grams)

c = specific heat capacity

∆T = change in temperature

m = 65g, specific heat capacity of water = 4.184J/g°C, initial temperature= 100°C, final temperature = 150°C

Q = 65 × 4.184 × (150 - 100)

Q = 271.96 × 50

Q = 13598 J

Hence, 13598 J of energy is required to boil 65 grams of 100°C water and then heat the steam to 150°C.

Answer:

A

Explanation:

there cnt be an increase photosynthesis.

surely when its cold,leaves dropped.

Explanation:

hope this can help youuu

Answer:

pioneer species, soil formation, plant growth

Explanation:

The events of succession after a volcano erupted in the proper order include pioneer species being visible. The pioneer species such as algae and Moss are usually found on rocks and dead matter.

After sometime the soil starts to form through weathering activities which then gives rise to and supports the growing of plant species.

Answer:

Reagent O₂ will be consumed first.

Explanation:

The balanced reaction between O₂ and C₄H₁₀ is:

2 C₄H₁₀ + 13 O₂ → 8 CO₂ + 10 H₂O

Then, by reaction stoichiometry, the following amounts of reactants and products participate in the reaction:

Being:

The molar mass of the compounds that participate in the reaction is:

Then, by reaction stoichiometry, the following mass quantities of reactants and products participate in the reaction:

If 78.1 g of O₂ react, it is possible to apply the following rule of three: if by stoichiometry 416 g of O₂ react with 116 g of C₄H₁₀, 62.4 g of C₄H₁₀ with how much mass of O₂ do they react?

[tex]mass of O_{2} =\frac{416grams of O_{2}*62.4 grams ofC_{4}H_{10} }{116 grams of C_{4}H_{10}}[/tex]

mass of O₂= 223.78 grams

But 21.78 grams of O₂ are not available, 78.1 grams are available. Since you have less mass than you need to react with 62.4 g of C₄H₁₀, reagent O₂ will be consumed first.

Answer: Nerve cells!

its the nerve cell which carry electrical message to others cell.

Answer:

The number of molecules in 895 g of H₂O is 4.49*10²⁵.

Explanation:

Avogadro's Number or Avogadro's Constant is called the number of particles that make up a substance (usually atoms or molecules) and that can be found in the amount of one mole of said substance. Its value is 6.023*10²³ particles per mole. Avogadro's number represents a quantity without an associated physical dimension, so it is considered a pure number that allows describing a physical characteristic without an explicit dimension or unit of expression. Avogadro's number applies to any substance.

In this case, the molar mass of compound H₂O is 18 g / mol. So if 18 grams of H₂O are present in 1 mole, 895 grams will be present in how many moles of H₂O?

[tex]moles of H_{2}O=\frac{895 grams*1 mole }{18 grams}[/tex]

moles of H₂O= 74.58

Then the following rule of three can be applied: if 1 mole of the compound contains 6.023 * 10²³ molecules by definition of Avogadro's number, 74.58 moles of the compound how many molecules will it contain?

[tex]amount of molecules=\frac{74.58 moles*6.023*10^{23}molecules }{1 mole}[/tex]

amount of molecules=4.49*10²⁵

The number of molecules in 895 g of H₂O is 4.49*10²⁵.

Answer:

his means 1 mole of butane has a volume of 22.4dm3 at STP. 1 mole of butane has the same mass in grams as its relative molecular mass.

Answer:

The answer to your question is A - electrons

Explanation:

To be honest it's pretty obvious, none of the other things could possibly come with valence behind it so electrons is the only logical answer.

Answer:

A. electrons

Explanation:

The valence electrons on the valence shell which is the last layer of electrons are the same for atoms in the same column.

Answer:

0 kgm/s

Explanation:

The momentum of Bob while resting at the river is 0 kgm/s.

This is because the momentum of any object at rest is 0.

 Momentum is the quantity of motion a body contains. It is mathematically expressed as;

  Momentum  = m x v

m is the mass

v is the velocity

 So at rest, the velocity of a body is 0m/s and therefore, the momentum is O

Answer: So the answer would be um I dont

know the answer right now but message me later on and I will help

Explanation: The equation that relates heat  (q) to specific heat (c_p) , mass (m), and temperature change  (Delta{T}) is shown below.

q=c_p times m times Delta{T}  The heat that is either absorbed or released is measured in joules. The mass is measured in grams. The change in temperature is given by Delta{T}= T_f - T_i , where  T_f is the final temperature and  T_i is the initial temperature. Step 1: List the known quantities and plan the problem .

Known

heat = q = 134 J

mass =  m = 15.0 g

Delta{text{T}} = 62.7^circ text{C} - 24.0^circ text{C} = 38.7^circ text{C}

Unknown

c_p text{of cadmium}= ? text{J}/ text{g}^circ text{C}

The specific heat equation can be rearranged to solve for the specific heat.

Step 2: Solve .

c_p=frac{q}{m times Delta{T}}=frac{134 text{ J}}{15.0 text{ g} times 38.7^circ text{C}}=0.231 text{ J/g}^circ text{C}

Step 3: Think about your result .

The specific heat of cadmium, a metal, is fairly close to the specific heats of other metals. The result has three significant figures.

Since most specific heats are known, they can be used to determine the final temperature attained by a substance when it is either heated or cooled. Suppose that a 60.0 g sample of water at 23.52°C was cooled by the removal of 813 J of heat. The change in temperature can be calculated using the specific heat equation.

Delta{T}=frac{q}{c_p times m}=frac{813 text{ J}}{4.18 text{ J/g}^circ text{C} times 60.0 text{ g}}=3.24^circ text{C}

Since the water was being cooled, the temperature decreases. The final temperature is:

T_f=23.52^circ text{C} - 3.24^circ text{C}=20.28^circ text{C}

Answer:

the answer is the second option

Explanation:

hope you have a great day though!

Answer:

0.1 im pretty sure

because

All those squares equal to 1

So if we use some good ole division

We get 0.1

Answer:

5

Explanation:

chemical formulas show what atoms are in a molecule.  In this case there is 1 hydrogen (H), 1 chlorine (Cl), and 3 oxygens (O).  The 3 behind the oxygen is a subscript and tells us that there are 3 oxygen atoms.

Another example is H2O which as 3 atoms. 2 hydrogens (H) and 1 oxygen (O).  This formula has a subscript 2 behind the hydrogen showing that there are 2 hydrogens.

Answer:

3 elements

Explanation:

Carbon, helium, and potassium