Answer:
1/4
Explanation:
From the question given above, the following data were:
Original amount (N₀) = 100 g
Time (t) = 24.8 h
Fraction remaining =?
NOTE: The half-life of K–42 is 12.4 h
Next, we shall determine the number of half-lives that has elapse. This can be obtained as follow:
Time (t) = 24.8 h
Half-life (t½) = 12.4 h
Number of half-lives (n) =?
n = t / t½
n = 24.8 / 12.4
n = 2
Finally, we shall determine the fraction remaining. This can be obtained as follow:
Number of half-lives (n) = 2
Fraction remaining =?
Fraction remaining = 1/2ⁿ
Fraction remaining = 1/2²
Fraction remaining = 1/4
Which type of change, chemical or physical, is a change on the atomic level?
Explanation:
Examples of chemical changes include, rusting, fire, and overcooking. Nuclear changes occur when the nuclei of atoms are rearranged to form new atoms. Examples of nuclear changes include atomic fission, nuclear fusion, and the energy of sun and stars.
Calculate the density (in grams per milliliter) of the following gas at 97 °C and 755 mm Hg Sulfur dioxide (SO2)
Answer:
Density = 2.09×10⁻³ g/mL
Explanation:
We solve this problem from the Ideal Gases Law.
P . V = n . R . T
We know that in STP conditions 1 mol of any gas occupies 22.4 L. So we can compare both situations.
22.4 L = 22400 mL
(P₁ . V₁) / T₁ = (P₂ . V₂) / T₂
We make some conversions:
97°C + 273 = 370 K
755 mmHg . 1 atm / 760mmHg = 0.993 atm
We replace data: (1 atm . 22400 mL) / 273 K = (0.993 atm . V₂) / 370 K
((1 atm . 22400 mL) / 273 K) . 370K = 0.993 atm . V₂
V₂ = 30359 atm . mL / 0.993 atm → 30573 mL
Under those conditions (97 °C and 755 mm Hg) 1 mol of gas is contained in 30573 mL.
We determine the amount of gas: 1 mol of SO₂ weighs 64.06g
Density = m/V → 64.06 g / 30573 mL = 2.09×10⁻³ g/mL
How many grams are in 0.75 moles of zinc?
Answer:
There are 65.38 grams are in 0.75 moles of zinc?
explain :We assume you are converting between moles Zinc and gram. You can view more details on each measurement unit: molecular weight of Zinc or grams The molecular formula for Zinc is Zn. The SI base unit for amount of substance is the mole. 1 mole is equal to 1 moles Zinc, or 65.38 grams.
I hope it will be helpful for youhelp asap pls getting timed !
Answer:
Calcium carbonate and citric acid.
Explanation:
Hello!
In this case, considering the text, we can notice that calcium carbonate combines with citric acid to produce the calcium citrate water and carbon dioxide as shown on the following equation:
[tex]3CaCO_3+2C_6H_8O_7\rightarrow Ca_3C_{12}H_{10}O_{14}+CO_2+H_2O[/tex]
Whereas the reactants, at the left side, are identified as calcium carbonate and citric acid.
Best regards!
How many sigma bonds and how many pi bonds are there in the tetracyanoethylene molecule
Answer:
Nine σ- and nine π
Explanation:
Nine σ- and nine π are there in the molecule of tetracyanoethylene.
the 2 written in this formula (2 CH4 is a)
Answer : 2 represent the coefficient.
Explanation :
As we know that:
The coefficients used in the chemical equations shows that the relative amounts of each substance present and this amount can represent either the relative number of molecules or number of moles.
If there is no coefficient then one (1) is assumed.
That means,
The coefficient tell us about that how many molecules or atoms present in the chemical equation.
By the stoichiometry we have to convert moles of a reactant to moles of a product.
The given formula is: [tex]2CH_4[/tex]
In this formula, 2 represent the coefficient and 4 represent the subscript and C and H represents the symbol of element.
Hence, 2 represent the coefficient.
How many grams of H2 are needed to react with 2.85 g of N2?
What is the density if the mass is 120g and the volume of the object is 96mL?
Answer:
1.25 g/cm^3
Explanation:
D = M/V
Mass is 120g
Volume is 96 ml
So you do 120/96 and you get your final answer as 1.25
Hope it helped!
Which one is convection??? A heater in a fish tank warming the water at the bottom of the tank, Batteries in a flashlight converting chemical energy into light, Touching a stove and burning your hand, or Warming up next to a fire on a cold night
Pleas help!!! I’ll make brainlist
Answer: 4.6 billion years ago
Explanation:
Answer:
4.6 billion years ago
hope this helps have a good day or night:)
66.41 g of Copper [Cu] are combusted with 8.56g of Oxygen [O] to produce a
compound. What is the empirical formula of the compound?
The empirical formula of the compound : Cu₂O
Further explanationGiven
66.41 g Cu
8.56 g O
Required
The empirical formula
Solution
1. Find mol
Cu(Ar 63.5 g/mol)mol = mass : Ar
mol = 66.41 : 63.5
mol = 1.046
O(Ar=16 g/mol)mol = 8.56 : 16
mol = 0.535
2. mol ratio
Cu : O (divide by smallest mol⇒0.535) :
[tex]\tt \dfrac{1.046}{0.535}\div \dfrac{0.535}{0.535}=2\div 1[/tex]
R equals The formula for Ohm's law can be written: R equals _____. I / V V / I I x V
Answer:
R = V / I
Explanation:
Ohm's Law:
V = I * R , V = voltage , I = current , R = resistance
rearranging to solve R,
R = V / I
Answer:
R = V / I
Explanation:
How many moles of Ca are in 1.25x1023 atoms?
We used two conversion factors in this unit, they are provided below. It is your responsibility to know which conversion factor to use!
Avogadro’s number: 6.02x1023 atoms = 1 mole
Molar mass of calcium: 40.078 g Ca = 1 mol Ca
A. 3.12x10^21 mol
B. 0.21 mol
C. 3.12 mol
D. 0.21x10^21 mol
B. 0.21 mol
General Formulas and Concepts:Math
Pre-Algebra
Order of Operations: BPEMDAS
Brackets Parenthesis Exponents Multiplication Division Addition Subtraction Left to RightChemistry
Atomic Structure
Using Dimensional AnalysisAvogadro's Number - 6.022 × 10²³ atoms, molecules, formula units, etc.Explanation:Step 1: Define
1.25 × 10²³ atoms Ca
Step 2: Identify Conversions
Avogadro's Number
Step 3: Convert
Set up: [tex]\displaystyle 1.25 \cdot 10^{23} \ atoms \ Ca(\frac{1 \ mol \ Ca}{6.022 \cdot 10^{23} \ atoms \ Ca})[/tex]Multiply: [tex]\displaystyle 0.207572 \ mol \ Ca[/tex]Step 4: Check
Follow sig fig rules and round. We are given 3 sig figs.
0.207572 mol Ca ≈ 0.208 mol Ca
Question (2) If your car
gets 27.8 miles to the gallon, how many liters of gasoline are necessary to travel 112 km?
This problem can be solved in short steps or in one longer step. In either case, please show your work.
Use the following conversion factors:
1 mi = 1.609 km
1 gal = 3.785 L
Answer:
9.48 L.
Explanation:
Hello!
In this case, as the problem mentions a long way to solve it, we are going to apply it because it can provide the answer more rapidly; thus, considering that 112 km are required, 1 mile equals 1.609 km and 1 gallon equals 3.785 liters, we can set up the proportional factor as shown below:
[tex]112km*\frac{1mi}{1.609 km}*\frac{1gal}{27.8mi}*\frac{3.785L}{1gal}[/tex]
Whereas km, mi and gal are cancelled out as it turns out in L; therefore the required liters are:
[tex]9.48L[/tex]
Best regards!
are all elements created equal? Provide evidence for why or why not.
An electron jumps from energy level 1 to energy level 2 by absorbing a photon of energy 8 eV. What is the most likely energy of the photon that will be emitted by the electron when it moves back down to energy level 1?
A. 2 eV
B. 4 eV
C. 8 eV
D. 12 eV
Answer:
C. 8 eV
Explanation:
In atoms, the energy of each level is quantised. That is one of the reasons why an electron can not exist between energy levels. Thus, when the electron absorbs energy of 8 ev, it get excited and jumps to energy level 2 which has the current value of energy of the electron.
Thus for the electron to move back to its initial energy level, it must emit the exact energy absorbed for its excitation. Therefore, the likely energy of the photon that will be emitted is 8 ev. This would make the electron to have energy that would make it to exist on energy level 1.
What is the energy change when a 777.1 g sample of water has
an initial temperature of 57.3 °C and a final temperature of
42.6 °C
Answer:
-47749.69 joule energy release.
Explanation:
Given data:
Mass of water = 777.1 g
Initial temperature = 57.3°C
Final temperature = 42.6 °C
Energy change = ?
Solution:
Specific heat capacity of water is 4.18 J/g.°C
Q = m.c. ΔT
Q = amount of heat absorbed or released
m = mass of given substance
c = specific heat capacity of substance
ΔT = change in temperature
ΔT = 42.6 °C - 57.3°C
ΔT = -14.7°C
Q = 777.1 g × 4.18J/g.°C × -14.7°C
Q = -47749.69 J
-47749.69 joule energy release.
in an electron dot diagram of fluorine , how many dots should be drawn around the elements symbol
Answer:
7 dots
Explanation:
Is the cell membrane a factory part or worker? Please explain what it does as a factory part or worker
Answer:
hey i saw you asked about the kinetic energy lab report on edg and i was wondering if you ever finished it and could send it me plzzzzzzzz
Explanation:
how do the properties of a mixture explain how they can be sepetated
Answer:
Mixtures are unlike chemical compounds, because: The substances in a mixture can be separated using physical methods such as filtration, freezing, and distillation.
Which best describes the changes occurring to the earth's surface over time?
1.) Mountains are gradually being worn down, but no new ones are formed
2.) New mountains are being formed as old mountains are gradually worn down
3.) More mountains are gradually formed as the oceans recede.
4.) New mountains are only formed under the oceans.
Answer:
I would say the answer is 2
The formation of new mountains due to tectonic movements is reporting now whereas, some of the olden mountains are worn down. Thus option 2 is correct.
What is tectonic movement?Earth crests is made of tectonic plates of different sizes and shapes. These plates were not apart and was one in the earlier times of earth and no separate continents were there. When heat in the atmosphere made the magma hot and the hot fluid flow makes the plate moving.
The tectonic plate movement is different in different regions and its results be different. Some movements results in the formation of mountains mostly when the plates are moving each other and one plate rise the edge of others.
Some movement results in islands, folded mountains, volcanic mountains etc. These mountains may worn down over time and there is a possibility of formation of new mountains in regions where significant plate movement occurs.
To find more about plate movement, refer the link bellow:
https://brainly.com/question/3970445
#SPJ2
A compound is found to contain 25.24 % sulfur and 74.76 % fluorine by weight. The molecular weight for this compound is 254.14 g/mol. What is the molecular formula for this compound
Answer:
[tex]S_2F_{10}[/tex]
Explanation:
Hello!
In this case, since the empirical formula of a chemical compound is determined by assuming the by-mass percentages are masses, we can firstly compute the moles of sulfur and fluorine based on their atomic masses:
[tex]n_S=25.24gS*\frac{1molS}{32.01gS}=0.789molS\\\\n_F=74.76gF*\frac{1molF}{19.00gF}=3.93molF[/tex]
Next, we compute the subscript of each element in the formula by dividing each moles by the fewest moles:
[tex]S=\frac{0.789}{0.789}=1\\\\F=\frac{3.93}{0.789} =5[/tex]
Whose molar mass is 127.01 g/mol. Now, we can compute the ratio between the molecular and empirical formulas as follows:
[tex]ratio=\frac{254.14}{127.01} =2[/tex]
Thus, the molecular formula is:
[tex]S_2F_{10}[/tex]
Regards!
Write the following elements in increasing order of atomic radius.
Ca, Mg, Be, Sr
Answer:
In increasing order:
Sr, Ca, Mg, Br
HELP ASAP! I will give brainiest if you answer all questions correctly.
28) Choose the best answer.
Calculate the amount of heat required or released. You will need to use your Periodic Table, Table B-3 and Table B-4, in your Chemistry Reference Guide.
How much heat is required to raise the temperature of 155 g of liquid ammonia (NH3) at 200 K to ammonia gas at 300 K? Ammonia boils at 240 K.
261 kJ
-204kJ
209kJ
-88kJ
300 kJ
29) Choose the best answer.
Calculate the amount of heat required or released. You will need to use your Periodic Table, Table B-3 and Table B-4, in your Chemistry Reference Guide.
How much heat would be needed to raise the temperature of 255 grams of ice at 253 K to steam at 393 K?
-204kJ
300 kJ
209kJ
-88kJ
788 kJ
30) Choose the best answer.
Calculate the amount of heat required or released. You will need to use your Periodic Table, Table B-3, Table B-4, and Table B-5 in your Chemistry Reference Guide.
How much heat is lost when 2012 g of H2O at 400 K is changed into ice at 263 K?
300 kJ
-880 kJ
299 kJ
-204 kJ
-6201 kJ
Answer:
28). 261
29). 788
30).-6201
Explanation:
I just took lesson and it said those were correct, I added screenshots of the lesson if you need it :)
A compound consists of atoms of two or more elements combined in a _______.
Answer: small, whole-number ratio
Explanation: 1) A compound consists of atoms of two or more elements combined in a small, whole-number ratio. In a given compound, the numbers of atoms of each of its elements are always present in the same ratio
Answer:
fixed proportion
Explanation:
The unit of electrical resistance is the: ohm-cm ohm volt ampere
Answer:
Ohm/ Current = Resistance
Explanation:
Answer:
Ohm
Explanation:
(3)
Calculate the entropy change when a sample of argon at 25 °C and 1.00 atm in a container
of volume 500 cm3 is compressed to 50 cm3 and cooled to -25 °C.
For argon, Cpm = 20.786) K-Imol-1. Assume that argon behaves perfectly.
Answer:
[tex]\Delta s=-23.0\frac{J}{mol*K}[/tex]
Explanation:
Hello!
In this case, since the entropy change when an ideal gas undergo both a volume and temperature change is computed by:
[tex]\Delta s =Cp*ln(\frac{T_2}{T_1} )-R*ln(\frac{P_2}{P_1} )[/tex]
Whereas the molar Cp is 20.786 J/(mol*K) and the final pressure is computed via the Boyle's law:
[tex]P_2=\frac{1.00atm*500cm^3}{50cm^3}=10 atm[/tex]
Thus, we plug in the data (temperatures in Kelvin) to obtain:
[tex]\Delta s =20.786\frac{J}{mol*K} *ln[\frac{(-25+273)K}{(25+273)K} ]-8.3145\frac{J}{mol*K}*ln(\frac{10atm}{1atm} )\\\\\Delta s=-23.0\frac{J}{mol*K}[/tex]
Best regards!
A neutral atom has the following electronic configuration: 1s2 2s2 2p6 3s2 3p5
How many protons are in the atomic nucleus and to which group of the periodic table does this element belong?
Answer:
Number of protons=17
Halogen
Explanation:
Given,
The electronic configuration:[tex]1s^2, 2s^2, 2p^6, 3 s^2, 3 p^5[/tex]
Atomic number= 2+2+6+2+5 = 17
Chlorine has the atomic number 17.
Symbol of chlorine= Cl
We know that,
The number of protons is equal to the atomic number.
Number of protons=17
And Chlorine belongs to the halogen group of the periodic table.
ltennelmessifcb avatar
ltennelmessifcb
45 minutes ago
Chemistry
Senior High School
You are given 600 grams of sodium chloride (NaCl), but you are planning to purify the substance and extract just the sodium. How many moles of Na can you theoretically extract from 600 grams of NaCl? Explain your reasoning.
Moles of Na theoretically extract : 10.256
Further explanationGiven
600 g of NaCl
Required
moles of Na
Solution
Na can be electrolyzed from NaCl(molten)
Na⁺ + e⁻⇒ Na
Cl⁻⇒1/2 Cl₂ + e⁻
Overall reaction :
NaCl⇒Na + 1/2 Cl₂ x2
2NaCl⇒2Na + Cl₂
mol of NaCl(MW=58.5 g/mol) :
= 600 g : 58.5 g/mol
= 10.256
From the equation, mol ratio of NaCl : Na = 2 : 1, so :
mol Na = mol NaCl = 10.256
2. How many Cu atoms have a mass of 4.500x10^5 amu?
Answer:
63.55
Explanation:
4.500 x 10^5 amu x 1 Cu atom / 63.55 amu = 7081 Cu Atom
Cu 1 x 63.55 = 63.55