Answer:
The number 872 would be written as,
8.72× 10²
Explanation:
Scientific notation is used to express the large value in short form.
The number in scientific notation have two parts.
First part:
The digits (decimal point will place after first digit)
Second part:
× 10 ( the power which put the decimal point where it should be)
For example the number 872 would be written as
8.72× 10²
Another example:
6324.4 in scientific notation will be written as = 6.3244 × 10³
The heat of fusion for naphthalene is 0.148 kJ/g. Calculate the heat energy in joules required to melt 52.95 g of naphthalene.
Answer:
7836.6 J
Explanation:
The following data were obtained from the question:
Heat of fusion (Hf) = 0.148 KJ/g
Mass (m) = 52.95 g
Heat (Q) required =..?
The heat (Q) required to melt the sample of nephthalene can be obtained as follow:
Q = m·Hf
Q = 52.95 × 0.148
Q = 7.8366 KJ
Finally, we shall convert 7.8366 KJ to Joule (J) in order to obtain the desired result. This can be obtained as follow:
1 kJ = 1000 J
Therefore,
7.8366 KJ = 7.8366 KJ × 1000 J / 1 KJ
7.8366 KJ = 7836.6 J
Therefore, 7.8366 KJ is equivalent to 7836.6 J
Thus, 7836.6 J of heat energy is required to melt the sample of nephthalene.
The heat required for melting of 52.95 g of naphthalene has been 7.8366 kJ.
The heat of fusion has been the energy required by 1g for the change in the substance.
The heat required to melt naphthalene can be given as:
Heat = mass × Heat of fusion
The given mass = 52.95 g
The heat of fusion = 0.148 kJ/g
The heat required can be given as:
Heat = 0.148 × 52.95 kJ
Heat = 7.8366 kJ.
The heat required for melting of 52.95 g of naphthalene has been 7.8366 kJ.
For more information about the heat of fusion, refer to the link:
https://brainly.com/question/25475410
The reaction between HCl and KOH results in an increase in temperature in the solution. Select the correct statement from the list below.
a) this is an endothermic reaction
b) this is a phase change reaction
c) this is a vaporization reaction
d) this is an exothermic reaction
Answer:
d) this is an exothermic reaction.
Explanation:
The reaction between HCl and KOH results in an increase in temperature in the solution. Select the correct statement from the list below.
a) this is an endothermic reaction . NO. This would cause a decrease in the temperature of the solution.
b) this is a phase change reaction . NO. All the species remain in the aqueous phase.
c) this is a vaporization reaction . NO. All the species remain in the aqueous phase.
d) this is an exothermic reaction. YES. The reaction releases heat, so it is exothermic.
Calculate the number of moles in 2.60 grams of SnO2 ? Please show your work to receive credit.
Answer:
There are 0.017252 moles in SnO2
Explanation:
n= m/M
n=2.6/(118.710 + 2(16))
n= 2.6/150.71
n= 0.017252
Remeber to round based on the significant digits in the question.
Help :( the blue boxes are clickable
Answer:
I am sure they are why won't they
Two students apply force to a box at rest on the floor.
Left
Right
40 Newtons
30 Newtons
What is the total amount of force in Newtons acting on the box and in which direction?
10 N Left
10 N Right
• 70 N Left
70 N Right
Answer:
10 N Left
Explanation:
Given parameters;
Forces acting on the box
Left force = 40N
Right force = 30N
Unknown:
Net force on the box and the direction = ?
Solution:
Force is a pull or push on a body;
← BODY →
40N 30N
The forces acting on the body are in the opposite directions, the greater force will determine the direction of pull.
Net force = Left force - Right force = 40 - 30 = 10N
The force will be directed left with a net value of 10N
Choose all the answers that apply.
Ionic compounds _____.
-do not dissolve in water
-have high melting points
-have low melting points
-dissolve easily in water
-conduct electricity when melted
Answer:
high melting points, dissolve easily in water, conduct electricity when melted.
Explanation:
I'm pretty sure
Members of which group easily lose an electron to form a +1 cation?
halogens
alkaline earth metals
noble gases
alkali metal
The alkali metals easily loose an electron and form a +1 cation.
The periodic table is arranged in groups and periods. The elements in the same group have the same number of valence electrons and similar chemical reactivity. This is why groups of elements are also called families of elements.
The group of the periodic table which its members easily loose electrons and form a +1 cation are the alkali metals.
Learn more:https://brainly.com/question/11857448
When a helium balloon rises in the air, it expands. If the volume of the balloon doubles, what happens to the density of the helium inside it?
a.The density decreases by half
b.The density doubles
c.The density triples
d.The density stays the same
what's the summary of matter
matter is anything that has mass and volume...it has three state thus solid, liquid and gas.. It possess chemical and physical changes.
The initial pressure of a mixture of C6H6 and an excess of H2 in a rigid vessel is 1.21 atm. A catalyst is introduced. After the reaction reaches completion, the temperature is restored to its initial value. The final pressure in the vessel is 0.839 atm. What was the mole fraction of C6H6 in the original mixture
Answer:
mole fraction of C6H6 = 0.613 atm
Explanation:
The equation for this reaction is :
[tex]C_6H_6 _{(g)} + 3H_2_{(g)} \to C_6H_{12}_{(g)}[/tex]
Initial P₁ P₂ 0
Final 0 P₂ -P₁/2 P₁
After completion of the reaction;
P₁ + P₂ = 1.21 atm ----- (1)
P₂ - P₁/2 + P₁ = 0.839 atm
P₂ + P₁/2 = 0.839 atm ----- (2)
Subtracting (2) from (1); we have:
P₁/2 = 0.371
P₁ = 0.742 atm
From(1)
P₁ + P₂ = 1.21 atm
0.742 atm + P₂ = 1.21 atm
P₂ = 1.21 atm - 0.742 atm
P₂ = 0.468 atm
Thus, the partial pressure of C6H6 = 0.742 atm
∴
Partial pressure = Total pressure × mole fraction of C6H6
mole fraction of C6H6 = Partial pressure / Total pressure
mole fraction of C6H6 = 0.742 atm / 1.21 atm
mole fraction of C6H6 = 0.613 atm
Condensation occurs with the removal of thermal energy.
True or False? If false, rewrite to make the question true.
PLZZZ HELP
Answer:
true
Explanation:
Condensation is the opposite of vaporization. True. When does condensation occurs, does a gas lose or gain thermal energy?
Answer:
True
Explanation:
Condensation is formed with moisture and cold air, so the removal of thermal energy, or heat, would create the perfect conditions :)
ppm is used to describe very small amounts of substance?
parts per million (ppm), parts per billion (ppb) and parts per trillion (ppt) are the most commonly used terms to describe very small amounts of substances. a ppm of a chemical in water means that, in a million units of water, there would only be one unit of the chemical.
State Hess' law of constant heat summation.
(b) Calculate the enthalpy of formation of CH4 from the following data:
i) C(s) + O2(g) → CO2(g); ∆H = -393.7 kJ/mol
ii) H2(g) + 1⁄2 O2(g) → H2O(l); ∆H = -285.8 kJ/mol
iii) CH4(g) + 2 O2(g)→ CO2(g) + 2H2O(l); ∆H = -890.4 kJ/mol
Answer:
-74.6 kj/mol
Explanation:
you can see the answer at the pic
A solution has a pH of 6. What is true about the solution?
A. It is a strong basic solution.
B. It is a weak acidic solution.
C. It is a weak basic solution.
D. It is a strong acidic solution.
please help me
Answer:
A. it is a strong basic solution
Answer:
(see below)
Explanation:
First, refer to the pH scale:
1 2 3 4 5 6 7 8 9 10 11 12 13 14
<== acidic neutral basic ==>
You can see that the smaller the number, the stronger the acid and the bigger the number, the more basic the base is. 7 is neutral, such as water. it's neither basic nor acidic.
Now, using the process of elimination:
A) It's a strong basic solution.
No, because this solution's pH hasn't even reached basic.
B) It's a weak acidic solution.
Yes, because it is acidic and it's just a little bit more acidic than a neutral solution.
C) It's a weak basic solution.
No, because this solution's pH hasn't even reached basic.
D) It's a strong acidic solution.
No, because even though it's acidic, it's just below neutral. For something to be a strong acidic solution would be around a pH of 3.
So the answer would be B) It's a weak acidic solution.
Which element is classified as a noble gas?
Answer:
The elements with completely filled shells are classified as noble gases
That is why we only see noble gases on the rightmost corner of the periodic table, it is because they have the maximum number of electrons in a shell
Examples of noble gases
Helium , Neon , Argon and Krypton are some examples of noble gases
Answer:
D. (Xe) XenonExplanation:
I JUST TOOK THE TEST!
how many moles of h2 can be made from the complete reaction of 3.5 moles of al?
Given: 2Al+6HCL 2Alcl3+3h2
Answer:
From the given equation, we can see that for every 2 moles of Al, we get 3 moles of H2
So, we can say the the number of moles of H2 is 3/2 times the number of moles of Al
We are given the number of moles of Al and we have to find the number of moles of H2
We have deduced the relationship:
Moles of Al * 3 / 2 = Moles of H2
Replacing the variables with given values
3.5 * 3 / 2 = Moles of H2
Moles of H2 = 5.25 moles
A student throws a 0.46kg bowling ball at a velocity of 25m/s what is the kinetic energy of the bowling ball in Joules
Answer:
The answer is 143.57 JExplanation:
The kinetic energy of an object can be found by using the formula
[tex]KE = \frac{1}{2} m {v}^{2} \\ [/tex]
where
m is the mass
v is the velocity
From the question we have
[tex]KE = \frac{1}{2} \times 0.46 \times {25}^{2} \\ = 0.23 \times 625[/tex]
We have the final answer as
143.75 JHope this helps you
An alkali metal with fewer than 10 protons in its nucleus
Answer:
Lithium (Li)
Explanation:
It has an atomic number of 3.
If it takes 26.0 mL of 0.0250 M potassium dichromate to titrate 25.0 mL of a solution containing Fe2 , what is the molar concentration of Fe2
Answer:
Explanation:
moles of potassium dichromate = .0250 x .026 = 65 x 10⁻⁵ moles
1 mole of potassium dichromate reacts with 6 moles of Fe⁺²
65 x 10⁻⁵ moles of potassium dichromate will react with
6 x 65 x 10⁻⁵ moles of Fe⁺²
= 390 x 10⁻⁵ moles
390 x 10⁻⁵ moles are contained in 25 mL of solution
molarity of solution = 390 x 10⁻⁵ / 25 x 10⁻³
= 15.6 x 10⁻² M .
A graduated cylinder is filled to an initial volume of 25mL. A solid object is dropped into the graduated cylinder. The final volume of the graduated cylinder is 60mL. The mass of the object is 140g. What is the density of the solid object?
Answer:
The answer is 4 g/mLExplanation:
The density of a substance can be found by using the formula
[tex]density = \frac{mass}{volume} \\ [/tex]
volume = final volume of water - initial volume of water
volume = 60 - 25 = 35 mL
From the question we have
[tex]density = \frac{140}{35} \\ [/tex]
We have the final answer as
4 g/mLHope this helps you
Help plzzzzzzzzzzzzzzz
Answer:
um wheres thepassage?
Explanation:
How many moles are in 141.16 grams of F?
Use two digits past the decimal for all values
Answer: 2681.81
Explanation:
What is the predictable process in which one element type is converted into a new form?Immersive Reader
(10 Points)
A. Law of Superposition
B. Igneous formation
C. Fossil formation
D. Radioactive decay
Answer:
Radioactive decay
Explanation:
Answer:
D. Radioactive decay
Explanation:
Radiation is transferring thermal energy by=
circulating fluids
touching/physical contact
electromagnetic waves
none of the above
which one is correct
HELPP
describe what potassium would do to be more stable
Answer:
Explanation:
Its a elemental potassium is soft ,white in colour and has one more electron than argon,an element that we know is extremely stable ... Potassium extra electron is easily lost to form the much more stable cation, K+
NEED HELP ASAP !
Which best describes an element?
A. elements are chemicals that are pure substance held together by chemical bonds
B. elements are mixtures of protons, neutrons, and electrons in different combination
C. elements are chemicals that are pure substances represented by symbols that have at least one capital letter
D. elements that are chemicals that are formed when temperature change happens or a precipitate forms
Answer:
A. Elements are pure substances.
Explanation:
Out of all four answers A would be best. Hope this helps.
Answer:
B
Explanation:
I think all options can define element in one form or another but an element is characterized by the atomic number it has i.e you will know it's Carbon due to it's number of protons, neutrons and/or electrons.
7. The equation below represents a chemical reaction that occurs in living cells.
CH,26 + 602
6CO2 + 6H,0 + energy
How many atoms are represented in the reactants of this equation?
A=6
B=12
C=24
D=36
Answer:
D
Explanation:
Because i just added all of numbers up
C. 24 if the zero after the 6H, is supposed to be a zero however if it wasnt and u were trying to say h2o it'd be 36
Ok
A plant part that contains a tiny new plant, or embryo
seed
spore
root
flower
Be sure to answer all parts.
Write a balanced equation for each reaction. Do not include states of matter to your equation.
H2 + O2 H20
Answer:
2H₂ + O₂ → 2H₂O
Explanation:
Chemical equation:
H₂ + O₂ → H₂O
Balance chemical equation:
2H₂ + O₂ → 2H₂O
Step 1:
H₂ + O₂ → H₂O
Left hand side Right hand side
H = 2 H = 2
O = 2 O = 1
Step 2:
H₂ + O₂ → 2H₂O
Left hand side Right hand side
H = 2 H = 4
O = 2 O = 2
Step 3:
2H₂ + O₂ → 2H₂O
Left hand side Right hand side
H = 4 H = 4
O = 2 O = 2
Based on the visible cell structures, which of the following statements is true?
All of the cells are plant cells.
All of the cells have chloroplasts.
All of the cells are animal cells.
All of the cells have a nucleus.