The original material has decayed 75%
Further explanationGiven
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
A 8.919 gram sample of an organic compound containing C, H and O is analyzed by combustion analysis and 12.65 grams of CO2 and 7.768 grams of H2O are produced. In a separate experiment, the molar mass is found to be 62.07 g/mol. Determine the empirical formula and the molecular formula of the organic compound.
Answer:
Empirical formula = CH₃O
Molecular formula = C₂H₆O₂
Explanation:
The empirical formula is the simplest whole-number ratio of atoms present in a molecule. To find the ratio of atoms we must find the moles of C, H and O. With the molar mass we can find the molecular formula:
Moles C = Moles CO₂:
12.65g * (1mol / 44.01g) = 0.2874 moles of C * 12.01g/mol = 3.452g C
Moles H = 1/2 moles H₂O:
7.768g * (1mol / 18.015g) = 0.4312 moles of H₂O * 2 = 0.8624 moles H * 1.008g/mol = 0.869g H
Moles O:
Mass O = 8.919g - 0.869g H - 3.452g C = 4.598g O * (1mol / 16g) = 0.2874 moles of O
Ratio of atoms -Dividing in the lower number of moles-:
C = 0.2874 mol C / 0.2874 mol = 1
H = 0.8624 mol H / 0.2874 mol = 3
O = 0.2874 mol O / 0.2874 mol = 1
Empirical formula = CH₃OThe molar mass of this formula is:
1C = 12.01g/mol
3H = 3*1.008g/mol = 3.024g/mol
1O = 16g/mol
12.01+3.024+16 = 31.034g/mol
Twice this formula gives the molecular formula = 31.034g/mol*2 = 62.068g/mol ≅ the molar mass of the compound. That means molecular formula of the compound is:
C₂H₆O₂HRISTINA HERRERA: Attempt 1
Question 9 (2.5 points)
3
Which of the following sets of data are consistent with the law of conservation of
matter?
6
7.5 g of hydrogen gas reacts with 50.0 g oxygen gas to form 57.5 g of water.
9
50 g gasoline reacts with 243 g oxygen to form 206 g of carbon dioxide and 97 g
water
12
17.7 g nitrogen react with 34.7 g oxygen to form 62.4 g nitrogen dioxide.
all of these
15
none of these
Answer:
7.5 g of hydrogen gas reacts with 50.0 g oxygen gas to form 57.5 g of water.
Explanation:
Here we have the check if the mass of the reactants is equal to the mass of the products.
Reactants
[tex]7.5+50=57.5\ \text{g}[/tex]
Products
[tex]57.5\ \text{g}[/tex]
The data is consistent with the law of conservation of matter.
Reactants
[tex]50+243=293\ \text{g}[/tex]
Products
[tex]206+97=303\ \text{g}[/tex]
The data is not consistent with the law of conservation of matter.
Reactant
[tex]17.7+34.7=52.4\ \text{g}[/tex]
Products
[tex]62.4\ \text{g}[/tex]
The data is not consistent with the law of conservation of matter.
Only the first data is consistent with the law of conservation of matter.
Which of the following compounds is formed by a covalent bond?
a. C6H12O6 b. NaBr c. CaCI2 d. NaCI
Answer: C6H12O6 is formed by a covalent bond, the rest of the options are formed by ionic bonds.
For the reaction 2Fe+o2 -->Feo how many grams of iron(ll) oxide are produced from 479.6 grams of iron in an excess of oxygen (Fe=56gmol, O=16g mol)
Mass of iron(ll) oxide= 616.608 g
Further explanationGiven
Reaction
2Fe+O2 -->2FeO
479.6 grams of iron
Required
mass of iron(ll) oxide
Solution
mol of iron :
= mass : Ar Fe
= 479.6 g : 56 g/mol
= 8.564
From the equation, mol FeO :
= 2/2 x mol Fe
= 2/2 x 8.564
= 8.564 moles
Mass of iron(ll) oxide :
= mol x MW
= 8.564 x 72 g/mol
= 616.608 g
Convert 5.802 g/cm^3 to Kg/L
Answer:
5.80200 Kg / L
Explanation:
Practice: Balance each of the chemical equations below. (Some equations may already be in balance.) In the space to the right, classify the reaction as a synthesis, decomposition, single replacement, or double replacement reaction. A. AgNO3 + KCl ???? AgCl + KNO3 B. H2O + SO3 ???? H2SO4 C. KI + Cl2 ???? KCl + I2 D. NaHCO3 ???? Na2CO3 + H2O + CO2 E. Zn + HCl ???? ZnCl2 + H2 F. BaCl2 + Na2SO4 ???? BaSO4 + NaCl G. C3H8 + O2 ???? CO2 + H2O H. Al + CuCl2 ???? AlCl3 + Cu
Explanation:
A. AgNO3 + KCl --> AgCl + KNO3
Reaction is already balanced.
Type = Double Replacement
B. H2O + SO3 --> H2SO4
Reaction is already balanced.
Type = Synthesis
C. KI + Cl2 --> KCl + I2
Balanced Equation = 2KI + Cl2 --> 2KCl + I2
Type = Single Replacement
D. NaHCO3 --> Na2CO3 + H2O + CO2
Balanced Equation = 2NaHCO3 --> Na2CO3 + H2O + CO2
Type = Decomposition
E. Zn + HCl --> ZnCl2 + H2
Balanced Equation = Zn + 2HCl --> ZnCl2 + H2
Type = Single Replacement
F. BaCl2 + Na2SO4 --> BaSO4 + NaCl
Balanced Equation = BaCl2 + Na2SO4 → 2NaCl + BaSO4
Type = Double Replacement
G. C3H8 + O2 --> CO2 + H2O
Balanced Equation = C3H8 + 5O2 → 3CO2 + 4H2O
Type = Single Replacement
H. Al + CuCl2 --> AlCl3 + Cu
Balanced Equation = 2Al + 3CuCl2 → 2AlCl3 + 3Cu
Type = Single Replacement
If two reactant molecules collide with each other what two reasons might they not combine ?
What is the theoretical yield of SO3 produced by 8.96 g of S?
Answer: Theoretical yield of [tex]SO_3[/tex] produced by 8.96 g of S is 33.6 g
Explanation:
To calculate the moles :
[tex]\text{Moles of solute}=\frac{\text{given mass}}{\text{Molar Mass}}[/tex]
[tex]\text{Moles of} S=\frac{8.96g}{32g/mol}=0.28moles[/tex]
The balanced chemical equation is:
[tex]2S+3O_2\rightarrow 2SO_3[/tex]
According to stoichiometry :
2 moles of [tex]S[/tex] produce = 3 moles of [tex]SO_3[/tex]
Thus 0.28 moles of [tex]S[/tex] will produce=[tex]\frac{3}{2}\times 0.28=0.42moles[/tex] of [tex]SO_3[/tex]
Mass of [tex]SO_3=moles\times {\text {Molar mass}}=0.42moles\times 80g/mol=33.6g[/tex]
Thus theoretical yield of [tex]SO_3[/tex] produced by 8.96 g of S is 33.6 g
Decide whether the element is a metal or nonmetal, if you can.
Element is a hard silvery-gray solid. Wires are fastened to each side of a 2 cm slab of it, and an ordinary household 9 V battery is hooked up so that it can feed electricity through the slab to an LED. But the LED stays dark
Answer:
The element is a nonmetal
Explanation:
Elements are broadly classified into metals and non metals. Metals conduct electricity while non metals do not conduct electricity.
If we look at this scenario described in the question, we can easily decipher that the element is a nonmetal because the LED stays dark. The LED should have been lit if electricity was passed through the element in question.
Hence, the element is a non metal.
The compound dioxane, which is used as a solvent in various industrial processes, is composed of C, H, and O atoms. Combustion of a 2.203-g sample of this compound produces 4.401 g CO2 and 1.802 g H2O. A separate experiment shows that it has a molar mass of 88.1 g/mol. What is the correct molecular formula for dioxane?
Answer:
[tex]C_4H_8O_2[/tex]
Explanation:
Hello!
In this case, since the combustion of this compound has only one source of carbon, the carbon dioxide, we can compute both mass and moles of carbon in 4.401 grams of CO2:
[tex]n_C = 4.401gCO_2*\frac{1molCO_2}{44.01gCO_2}* \frac{1molC}{1molCO_2} =0.1molC\\\\m_C = 0.1molC*\frac{12.01gC}{1molC} = 1.201gC[/tex]
Next, we do the same for hydrogen in water, as the only source of this atom in the products:
[tex]n_H = 1.802gH_2O*\frac{1molH_2O}{18.02gH_2O}* \frac{2molH}{1molH_2O} =0.2molH\\\\m_H = 0.2molC*\frac{1.01gH}{1molH} = 0.202gH[/tex]
Thus, we compute the mass and then the moles of oxygen considering the 2.203-g sample of dioxane:
[tex]m_O = 2.203g-m_C-m_H=2.203g-1.202g-0.202g = 0.799gO\\\\n_O =0.799gO*\frac{1molO}{16.0gO} =0.05molO[/tex]
Next, we divide the moles of C, H and O by the moles of O as the fewest in the molecule to find their subscripts in the empirical formula:
[tex]C:\frac{0.1mol}{0.050mol}=2 \\\\H:\frac{0.202mol}{0.050mol} =4\\\\O:\frac{0.050}{0.050}=1 \\\\[/tex]
[tex]C_2H_4O[/tex]
Whose molar mass is 44.1 g/mol. Thus, since the molar mass of the compound is 88.1 g/mol, we see a factor of 2 by which the empirical formula should be multiplied to get the molecular one, therefore, we obtain:
[tex]C_4H_8O_2[/tex]
Best regards!
If one iron nail weighs 2.0 grams, what would be the mass of 6.022 x 10^23 nails?
Answer:
[tex]1.2x10^{24}g[/tex]
Explanation:
Hello!
In this case, it is possible to treat this problem by using a proportional factor which indicates one iron nail equals 2.0 grams:
[tex]\frac{2.00g}{1nail}[/tex]
Now, for an amount of 6.022x10²³ nails, the corresponding mass will be:
[tex]6.022x10^{23}nail*\frac{2.00g}{1nail} \\\\1.2x10^{24}g[/tex]
Best regards!
The rate constant (k) for a reaction was measured as a function of temperature. A plot of ln k versus 1>T (in K) is linear and has a slope of -1.01 * 104 K. Calculate the activation energy for the reaction.
Answer:
8.397J/mol is the activation energy for the reaction
Explanation:
The graphical form of Arrhenius equation is:
ln k = -Ea/R*(1/T)+lnA
Where k is activation energy
Ea is activation energy
R is gas constant (8.314J/molK)
T is absolute temperature
And A is the pre-exponential factor.
The slope of the plot is -Ea/R:
-Ea/R = -1.01x10⁴K
-Ea/8.314J/molK = -1.01x10⁴K
Ea = -1.01x10⁴K*8.314J/molK
Ea = 8.397J/mol is the activation energy for the reaction
If 1000g of water from Luboc River contains 0.0075g of Ca2+ ion, what is the concentration in ppm by mass of Ca2+ present in Luboc River?
7.5 ppm
Further explanationGiven
1000 g of water
0.0075g of Ca²⁺ ion
Required
the concentration in ppm by mass of Ca²⁺
Solution
ppm = part per million
solvent = water ⇒ ppm = 1 mg/L(water density is 1 kg / L) or mg/kg
Convert g to mg of Ca²⁺ ion :
0.0075 g = 7.5 x 10⁻³ g = 7.5 mg
Convert g to kg of water :
1000 g = 1 kg water
So the concentration of Ca²⁺ ion :
= 7.5 mg / 1 kg
= 7.5 ppm
you
12. Choose one famous MLK quote as
Favorite and explain why that is your
favorite?
Which natural resource is limited in supply?
)
A)
wind
B)
petroleum
C)
water power
D)
solar energy
Used by nearly one-third of the U.S. population, _________________ are frequent sources of biological contamination, such as fecal bacteria and virus contamination, of water supplies, and often the owners of these systems dispose of detergents, nitrates, chlorides, and solvents in the system leading to potential downstream contamination if not managed properly.
Answer:
Septic tanks.
Explanation:
Wastewater typically refers to a body of water that has been contaminated through human use in homes, offices, schools, businesses, etc. Wastewater are meant to be disposed in accordance with the local regulations and standards because they are unhygienic for human consumption or use.
Generally, many homes use a floor drain in their bathrooms and toilets to remove wastewater in order to mitigate stagnation and to improve hygiene. A floor drain can be defined as a material installed on floors for the continuous removal of any stagnant wastewater in buildings.
Wastewater flows into a septic tank once it is released into a floor drain or from the water closet through the use of a pipe such as a polyvinyl chloride (PVC) pipe, which directly connects the to the septic tank.
It is used by nearly one-third of the U.S. population, septic tanks are frequent sources of biological contamination, such as fecal bacteria and virus contamination, of water supplies, and often the owners of these systems dispose of detergents, nitrates, chlorides, and solvents in the system leading to potential downstream contamination if not managed properly.
Hence, the wastewater and biological contamination should be removed from septic tanks when they are filled up through the use of a pump.
A strong acid is used as a titrant against a weak base. What would be the most likely pH for the equilibrium point?
Answer:
Below 7
Explanation:
The equivalence point, or stoichiometric point, of a chemical reaction is the point at which chemically equivalent quantities of reactants have been mixed(Wikipedia).
For a strong acid-weak base titration, the pH at the equivalence point is usually below 7. This owes to the fact that a conjugate acid is produced in the course of the reaction which interacts with water to produce hydronium (H3O+) ions.
Answer:
7
Explanation:
i did my research and from what i found its 7.
HELPPPP PLZ
A student pushes a 40-N block across the floor for a distance of 10 m.
How much work was done to move the block?
400 Pascals
400 Newtons
400 Joules
400 Watts
400 Joules
Work done is measured in Joules (J) remember that
Answer:400 joules
wut do u need
Explanation:
Does warm air rise or fall?
rise and cold air
it doesn't fall cause I already fall inlove with levi
atoms are composed of subtomatic particles called
Why did the Ahmet family have to leave their home? A- They could no longer afford to live there. B-They were asked to leave by the government. C-Their home was destroyed by a bomb. D-Violence broke out in the village that they lived in.
Answer:
c). their home was destroyed by the government
Explanation:
yan po ang Tama sure ako sa sagot ko.
Nitrates are _____.
compounds made from carbon dioxide
used by plants to make protein
released into the atmosphere by respiration
are harmful to the environment
Answer:
used by plants to make protein
Explanation:
so B
There are
molecules of carbon dioxide (CO2) in 102.5 grams.
Answer:
1.403x10²⁴ molecules
Explanation:
In order to calculate how many molecules of CO₂ are there in 102.5 g of the compound, we first convert grams to moles using its molar mass:
102.5 g ÷ 44 g/mol = 2.330 mol CO₂Now we convert moles into molecules using Avogadro's number:
2.330 mol * 6.023x10²³ molecules/mol = 1.403x10²⁴ moleculesHuman induced phenomena that cause global
warming
(Need at least 3)
Answer:
Burning of fossil fuels
Cutting of tress
Also CO2 is produce in industries like cement manufacturing.
Explanation:
What is the percent composition of Mg in the compound Mg3(PO4)2?
A 21.92%
B 23.57%
C 32.32%
D 27.74%
Answer:
D 27.74%
Explanation:
Percent composition of Magnesium (Mg) in Magnesium Phosphate compound ie Mg3(PO4)2 = 27.74%
Answer:
The answer is D
Explanation:
I took the test
How many elements are in k2HPO4
How many moles of O2 are in 125 grams of CO2?
(this is a gram to mole conversion) HELP ME PLEASE!!!
Answer:
20 mole of co2
Explanation:
I hope this helps
Determine what happens in this reaction.S + Cl2 →SCl2
Sulfur act as a reducing agent and chlorine acts as an oxidizing agent.
Oxidation: The loss of electronsReduction: The gain of electronsOxidation number:The charge is based on the number of electrons assigned to an atom as compared to the neutral atom
Given reaction:-
[tex]S+Cl_2 \rightarrow SCl_2[/tex]
The oxidation state of sulfur in the left side is 0, but in right side is +2. So, sulfur is oxidized. The oxidation number of Cl in the reactant side is 0 and n the product side is -1. So, Cl acts as oxidizing agent.
To know more about:-
brainly.com/question/13182308
A chemist prepares a solution of calcium bromide by measuring out of calcium bromide into a volumetric flask and filling the flask to the mark with water. Calculate the concentration in of the chemist's calcium bromide solution. Be sure your answer has the correct number of significant digits.
Answer:
6.76 mol/L
Explanation:
A chemist prepares a solution 0.607 kg of calcium bromide by measuring out of calcium bromide into a 450. mL volumetric flask and filling the flask to the mark with water. Calculate the concentration in mol/L of the chemist's calcium bromide solution. Be sure your answer has the correct number of significant digits.
Step 1: Given data
Mass of calcium bromide (solute): 0.607 kg (607 g)Volume of solution (V): 450. mLStep 2: Calculate the moles of solute
The molar mass of calcium bromide is 199.89 g/mol.
607 g × 1 mol/199.89 g = 3.04 mol
Step 3: Convert "V" to liters
We will use the conversion factor 1 L = 1000 mL.
450. mL × 1 L/1000 mL = 0.450 L
Step 4: Calculate the concentration of calcium bromide in mol/L
[CaBr₂] = 3.04 mol/0.450 L = 6.76 mol/L
Which organism would most likely belong to the plant kingdom?
Answer:
tree
Explanation:
so easy and obvious