Indicate whether each statement is true or false.

a. When a solution is made, the enthalpy of mixing is always a positive number.
b. An increase in entropy favors mixing.
c. A solute will dissolve in a solvent if solute-solute interactions are stronger than solute-solvent interactions.

Answer:

There are two atoms in one hydrogen molecule.

Explanation:

Hello!

In this case, when going over chemical reactions, we need to realize about the amount of atoms of each element; thus, according to the given chemical reaction by which water is formed:

[tex]H_2+O_2\rightarrow H_2O[/tex]

It is seen there are two hydrogen atoms in the hydrogen molecule, two in oxygen and two hydrogen atoms and one oxygen atom in water; however, these reactions must be balanced according to the law of conservation of mass:

[tex]2H_2+O_2\rightarrow 2H_2O[/tex]

Which means we have two hydrogen molecules with two atoms each, one oxygen molecule with two atoms and two water molecules with two hydrogen atoms and one oxygen atom each.

Best regards!

Answer:

Number of moles = 0.1179 (Approx)

Explanation:

Given:

Mass of LiCl = 5 grams

Molar mass of LiCl = 42.39 g

Find:

Number of moles

Computation:

Number of moles = Mass / Molar mass

Number of moles = 5 / 42.39

Number of moles = 0.1179 (Approx)

Among the given options the compound with the formula C₃H₈ is option C. It is an organic compound under named as propane.

What is propane?

Propane is an organic compound classified as a hydrocarbon  with saturated carbon - hydrogen bonds. It's formula is C₃H₈. It contains 3 carbons and 8 hydrogens.

The two end carbons contains 3 hydrogens each and the middle carbon contains 2 hydrogens. They are all bonded through sigma bonding. The compound in A is C₅H₁₂ and in B, it is C₆H₁₄.

The formula of the compound in option D is C₅H₁₀. Hence, the skeleton showing the compound with the formula of C₃H₈ is option C.

To find more on propane, refer here:

https://brainly.com/question/24159489

#SPJ2

Answer:

68.22656

Explanation:

I think this is the answer.

Hope it's correct!

Answer:

68.22656

Explanation:

Speed

30.500001382

Meter per second

=  

68.22656

Miles per hour

Formula  

multiply the speed value by 2.237

(hope this helps can i plz have brainlist :D hehe)

Answer:

The answer to this problem is C

The original material has decayed 75%

Given

two half-life

Required

The decayed sample

Solution

General formulas used in decay:  

[tex]\large{\boxed{\bold{N_t=N_0(\dfrac{1}{2})^{t/t\frac{1}{2} }}}[/tex]

t = duration of decay  

t 1/2 = half-life  

N₀ = the number of initial radioactive atoms  

Nt = the number of radioactive atoms left after decaying during T time

t = 2 x t 1/2

Input the value :

[tex]\tt \dfrac{Nt}{No}=\dfrac{1}{2}^2=\dfrac{1}{4}=25\%[/tex]  

The amount of Nt = 25% No

Answer:

the answer is 1,2,2,3

Explanation:

Fe3O4 +C ---> CO2 + Fe

1Fe3O4 +2C ---> 2CO2 + 3Fe

Answer:

0.246 moles

Explanation:

Aluminum Sulfate is an ionic equation so we need to write the equation first with proper charges and subscripts:

Now that we know the ionic equation, we need to find the molar mass of Al_2(SO4)_3. There's 2 Aluminum's, each weighing 26.98 g/mol. There are 3 sulfates, each sulfate weighs 96.06 g/mol. We need to multiply the number of elements/compounds by their mass to get the total molar mass and then add them up (remember atomic mass = molar mass in g/mol):

We now know the molar mass of Al_2(SO4)_3 we need to find how many moles of it there are in an 84.2g sample. To do that, we need to do some dimensional analysis:

The grams of Al_2(SO4)_3 cancel so that we're left with moles of Al_2(SO4)_3 on top:

So in an 84.2g sample of Al_2(SO4)_3 (aka aluminum sulfate), there are 0.246 moles. This is correct because in one mole of Al_2(SO4)_3, there are 342.15g and the sample of 84.2 g of Al_2(SO4)_3 is way smaller than that, so our answer should be less than one mole, which it is.

I hope this helped!

This question is incomplete, the complete question is;

Consider an experimental setup with two compartments separated by a phospholipid bilayer membrane containing ion channels selectively permeable only to chloride ions. The left compartment (also called inside) contains 1 mM Cl- and the right compartment (also called outside) contains 100 mM Cl-. What will the electrical potential be when the system attains equilibrium? [ assume body temperature; log 100 = 2, log 10 = 1, log 1 = 0, log 0.1 = -1, log 0.01 = -2]

Options;

a) -62 mV

b) -124 mV

c) +62 mV

d) 0 mV

e) +124 mV

Answer:

the electrical potential be when the system attains equilibrium is  –124mV

Option b) –124mV is the correct answer

Explanation:

Given the data in the question;

Two compartments are divided by lipid bilayer;

In inside compartment Cl- ion concentration- 1mM and out side of the cell concentration is 100mM

now we apply the Nernst equilibrium potential equation;

Chlorine ion valency is z = –1

So

[tex]E_{eq}[/tex] = 62/z × log(ion outside/ ion inside) [for Cl‐ ions]

[tex]E_{eq}[/tex] = (62 / –1) x log(  100 / 1 )

 [tex]E_{eq}[/tex] = -62 x 2 =

[tex]E_{eq}[/tex]  = –124mV

Therefore, the electrical potential be when the system attains equilibrium is  –124mV

Option b) –124mV is the correct answer

Answer:

Option B & Option C

Explanation:

correct on edge! :D

When chemicals combine chemical change takes place which is accompanied by emission of heat and light.

Chemical changes are defined as changes which occur when a substance combines with another substance to form a new substance.Alternatively, when a substance breaks down or decomposes to give new substances it is also considered to be a chemical change.

There are several characteristics of chemical changes like change in color, change in state , change in odor and change in composition . During chemical change there is also formation of precipitate an insoluble mass of substance or even evolution of gases.

There are three types of chemical changes:

1) inorganic changes

2)organic changes

3) biochemical changes

During chemical changes atoms are rearranged and changes are accompanied by an energy change as new substances are formed.

Learn more about chemical change,here:

https://brainly.com/question/23693316

#SPJ5

Answer:

1.5055×10²⁴ molecules

Explanation:

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

Number of mole CO₂ = 2.5 moles

Number of molecules CO₂ =?

The number of molecules present in 2.5 moles CO₂ can be obtained as:

From Avogadro's hypothesis,

1 mole of CO₂ = 6.022×10²³ molecules

Therefore,

2.5 mole of CO₂ = 2.5 × 6.022×10²³

2.5 mole of CO₂ = 1.5055×10²⁴ molecules

Thus, 1.5055×10²⁴ molecules are present in 2.5 moles CO₂

Answer: b. 322.5 mL

Explanation:assume constant pressure, then

693/(273.15+45) = v/(273.15-125)

v= 693*148.15/318.15 = 322.7

By using Charles law, the volume will be 322.5 mL

What is Charle's law?

The volume of such an ideal gas is proportional to its absolute temperature at constant pressure, according to Charles' law.

According to Charles law.

[tex]T_{1} / T_{2} = V_{1} / V_{2}[/tex]

where, T is temperature and V is volume.

A substance or object's volume refers to the amount of 3D space it takes up.

Calculation of volume.

Given data:

V = 693 mL

[tex]T_{1}[/tex] =-125°C = (273-125) = 148 K

[tex]T_{2}[/tex] = 45° = (273+45) = 318 K

Put the value of given data in Charles law formula.

148 K/  318 K = V / 693 mL

V = 322.5 mL.

Therefore, by using Charles law the volume of a gas will be 322.5 mL.

To know more about Charles law.

https://brainly.com/question/16927784

#SPJ2

Answer:

no, and next time take it right

Explanation:

Answer:

a)

[tex]K = 2.64 * 10^{-8}[/tex]

b)

[tex]15 \frac{5}{8}[/tex] hours

Explanation:

Given

Surface Area (S) of 250 grams of powder sample [tex]= 250[/tex] square meter.

[tex]S = 2500000[/tex] square centimeter

[tex]V\frac{dC}{dT} = 0.40[/tex] grams/minute

[tex]V\frac{dC}{dT} = \frac{dM}{dT} = \frac{0.40*60}{10} = 0.66[/tex] mg per second

[tex]C_s = 0.01[/tex] gram per cubic meter [tex]= 10[/tex] mg/ml

a)

[tex]\frac{dM}{dT} = K SC_s[/tex]

[tex]0.66 = K* 2500000* 10\\[/tex]

[tex]K = 2.64 * 10^{-8}[/tex] cm /sec

b) Time taken

Time taken to sink

[tex]\frac{10*60}{0.4} * 37.5 = 56,250[/tex]

Time in hours

[tex]15 \frac{5}{8}[/tex] hours

Answer:

The better solvent for separating the mixture of A and B is dichloromethane

Explanation:

Petroleum ether is the mixture of hydrocarbons obtained from the petroleum distillation with a boiling range between 35 and 60°C. Is used as a solvent.

In the other hand, the best solvent for separating a mixture in TLC is the one that has the higher difference between RF's of the compounds.

The difference in RF's in dichloromethane is:

|0.44 - 0.69| = 0.25

In petroleum ether:

|0.29 - 0.45| = 0.16

That means the better solvent for separating the mixture of A and B is dichloromethane

Answer: The new temperature of the water bath is [tex]31.9^0C[/tex]

Explanation:

The quantity of heat required to raise the temperature of a substance by one degree Celsius is called the specific heat capacity.

[tex]Q=m\times c\times \Delta T[/tex]

Q = Heat released by water =[tex]69.0kJ=69000J[/tex]     (1kJ=1000J)

m= mass of water = 8.10 kg= 8100 g   (1kg=1000g)

c = specific heat capacity = [tex]4.184J/g^0C[/tex]

Initial temperature of the water = [tex]T_i[/tex] = [tex]33.9^0C[/tex]

Final temperature of the water = [tex]T_f[/tex]  = ?

Change in temperature ,[tex]\Delta T=T_f-T_i[/tex]

Putting in the values, we get:

[tex]-69000J=8100g\times 4.184J/g^0C\times (T_f-33.9)^0C[/tex]

[tex]T_f=31.9^0C[/tex]

The new temperature of the water bath is [tex]31.9^0C[/tex]

Answer:

Explanation:

Iron Haber process  = (making ammonia)

Vanadium (V) oxide = Contact process (a stage in making sulfuric acid)

Manganese dioxide = Decomposition of hydrogen peroxide (produces water and oxygen)

Answer:

See answer below

Explanation:

Let's write the equation again:

H₂ + O₂ ---------> H₂O

Now that we have written the equation, let's solve the exercise:

1. In this case, we first need to make a difference between atom and molecule. An atom is just a single element, a molecule it's when you have more than 1 element in a compound.

Knowing this, we have the H₂. In this case we only have one element, Hydrogen. However, as you can see in the expression, we have a number 2 as a subscript. The number 2 means that the hydrogen it's not alone, we do not have one hydrogen, we have two hydrogens, therefore, it becomes a molecule. Now, This molecule, according to the number 2 as subscript, means that the molecule of hydrogen have 2 atoms of hydrogens, and this formed the molecule, therefore, there are 2 atoms of hydrogens in H₂.

2. Following the same explanation of above, but using oxygen, we have the same thing, so, in a molecule of O₂, we have 2 atoms of oxygen.

3. The molecule of water is composed of Hydrogen and oxygen. As you can see, in this case we have 2 hydrogen and 1 oxygen, therefore, in 1 molecule of water, there are 1 atom of oxygen and 2 atoms of hydrogen.

4. The subscript, as you may know now, tell us the number of atoms that you have in a molecule or compound. This number also means, in different compounds the oxidation state of the atoms that conform the molecule.

5. No, the equation is not balanced, because we do not have the same number of oxygen on the side of the products. We need to balance that. As the oxygen is unbalanced, we just need to put numbers as coefficients, behind the molecule. This number will multiply the number of atoms of the referred molecule. So, doing this with the water on the products to equal the number of oxygen, we have:

H₂ + O₂ ---------> 2H₂O

But this 2, unbalance at the same time the number of hydrogens. We now have 4 hydrogens in the product, so, to balance this, we put a 2 on the reactants:

2H₂ + O₂ ---------> 2H₂O

Now the reaction is balanced.

Hope this helps

Answer:

Kb[tex]= 1.58 * 10^{-6}[/tex]

Explanation:

The correct question is

What is Kb for N2H4 if the pH of a 0.158M solution of N2H5Cl is 4.5?

Solution-

N2H4Cl hydrolyses on addition of water

The reaction equation is as follows -

N2H4+ + H2O ----> N2H4 + H3O+

[tex]Ka = \frac{K_w}{K_b} = \frac{10^{-14}}{K_b}[/tex]

pH [tex]= 4.5[/tex]

[tex][H+] = 10^{-pH} = 10^{-4.5}[/tex]

[tex]K_b= \frac{10^{-14} }{K_b} = \frac{Y_2}{0.158} \\K_b= \frac{(10^{-4.5})^2}{0.158}\\=> Kb = 0.158 * 10-14 /(10-4.5)2[/tex]

 Kb[tex]= 1.58 * 10^{-6}[/tex]

Answer:

13.3 h

Explanation:

Step 1: Given data

Time (t): 48,000 seconds

Step 2: Convert "t" from seconds to minutes

We will use the conversion factor 1 min = 60 s.

48,000 s × 1 min/60 s = 800 min

Step 3: Convert "t" from minutes to hours

We will use the conversion factor 1 h = 60 min.

800 min × 1 h/60 min = 13.3 h

To sum up, 48,000 seconds is equal to 13.3 hours.

Answer:

The metallic oxide is Li₂O

Explanation:

Let the metallic oxide be M₂O

Thus;

M₂O + H₂ = 2M + H₂O

Molar mass of M₂O = (2x + 16)

We assume Molar mass of M to be x.

We are told that 5.00 g of the metallic oxide produces 2.32 g of the metal.

By proportion, we can write the following;

5g of M₂O × (1 mole of M₂O/(2x + 16)) × (2 moles of M/1 mole of M₂O) = 2.32 g of M × 1 mole of M/x g of M

This cancels out to give us;

10/(2x + 16) = 2.32/x

Cross multiply to get;

10x = 2.32(2x + 16)

10x = 4.64x + 37.12

10x - 4.64x = 37.12

5.36x = 37.12

x = 37.12/5.36

x = 6.925 g/mol

The metal with a molar mass closest to this value of x is Lithium which has a molar mass of 6.94 g/mol

Thus the metal is Lithium and as such the metallic oxide is Li₂O

Answer:

88.46%

Explanation:

Percentage yield is actual/theoretical * 100

138/156 * 100 = 88.4615385

Explanation:

ksiiaisisjjsjajajhahajajjalañLzlzl

Explanation: A . upwelling .

Answer:

D. The cork looked like tiny rectangular rooms

Explanation:

The invention that helped scientists discover the cell is the microscope. Tell why Hooke called the structures he saw in the cork cellular("small rooms"). He called them cellular because the box like cells reminded him of the monks monasteries.

Answer:

2,47 * [tex]10^{24}[/tex] (molecules)

Explanation:

Avogadro's number is a very important relationship: 1 mole = 6,02 * [tex]10^{23}[/tex] atoms, molecules, protons, etc.

To convert from moles to molecules, multiply the molar amount by Avogadro's number.

4,1 mol * 6,02 * [tex]10^{23}[/tex]  ≈ 24,7 * [tex]10^{23}[/tex] = 2,47 * [tex]10^{24}[/tex] (molecules)

Therefore the third answer is correct

B) oxygen is oxidized.

Given

photosynthesis reaction

6CO2 + 6H20 ⇒ C6H12O6 + 602

Required

the oxidation compound

Solution

Oxidation-reduction reactions or abbreviated as Redox are chemical reactions in which there is a change in oxidation number

Oxidation is an increase in oxidation number, whereas Reduction is a decrease in oxidation number.

In the photosynthetic reaction, oxidation and reduction reactions occur in:

CO2 to C6H12O6 : reduction

Oxidation number of C from +4 to 0

H2O to O2 : oxidation

Oxidation number of O from -2 to 0