Answer: e. 4.8 h
Explanation:
Expression for rate law for first order kinetics is given by:
[tex]t=\frac{2.303}{k}\log\frac{a}{a-x}[/tex]
where,
k = rate constant
t = age of sample
a = let initial amount of the reactant
a - x = amount left after decay process
a) for rate constant
Half life is the amount of time taken by a radioactive material to decay to half of its original value.
[tex]t_{\frac{1}{2}}=\frac{0.693}{k}[/tex]
[tex]k=\frac{0.693}{0.77hr}=0.9hr^{-1}[/tex]
b) for 160.0 g to decay to 2.07 g
[tex]t=\frac{2.303}{0.9}\log\frac{160.0}{2.07}[/tex]
[tex]t=4.8hr[/tex]
The time required for a 160.0-g sample of 158Eu to decay to 2.07 g is 4.8 hours
The Earth and the spaceship both have mass. The astronaut is attracted to Earth by gravity, but he is not attracted to the spaceship. Explain.
What is the electron configuration for N (nitrogen)?
A. 1s22s23s23p1
B. 1s21p5
C. 1s22s22p3
D. 1s22s22p23s1
Explanation:
₇N = 1s² 2s² 2p³
Group = 15period = 2atomic mass = 14Hydride of Nitrogen = Ammoniavalency = 3Therefore,
Option C is correct ✔
How many mL of 0.125 M Ba(OH)2 would be required to completely neutralize 75.0 mL of 0.845 M HCl? What is the pH of the solution at the equivalence point?
Answer:
253.5mL of Ba(OH)₂ are required to neutralize the HCl solution
The pH at equivalence point is = 7
Explanation:
The reaction of Ba(OH)₂ with HCl is:
Ba(OH)₂ + 2HCl → BaCl₂ + 2H₂O
First, we need to find moles of HCl. With these moles and the chemical equation we can find the moles of Ba(OH)₂ and the volume required:
Moles HCl:
75.0mL = 0.075L * (0.845mol / 1L) = 0.063375moles HCl
Moles Ba(OH)₂:
0.06338moles HCl * (1mol Ba(OH)₂ / 2mol HCl) = 0.03169 moles Ba(OH)₂
Volume of the 0.125M Ba(OH)₂:
0.03169 moles Ba(OH)₂ * (1L / 0.125mol) = 0.2535L are required =
253.5mL of Ba(OH)₂ are required to neutralize the HCl solution
As the titration was of a strong acid, HCl, with a strong base, Ba(OH)₂, the pH at equivalence point is = 7
A compound with a formula mass of 45.08 g/mol is found to be 85.64% Carbon and the remainder Hydrogen. Find the molecular formula:
An ice cube melts on the warm sidewalk on a hot summer day. Let the entropies of the ice cube, of the pavement and of the ice cubesidewalk system be Sice, Ssw and Ssys. What happens to these entropies?
1. Sice increases, Ssw decreases, Ssys does not change.
2. Sice decreases, Ssw increases, Ssys decreases
3. Sice increases, Ssw decreases, Ssys increases
4. Sice increases, Ssw increases, Ssys increases
Answer:
3. Sice increases, Ssw decreases, Ssys increases
Explanation:
Entropy basically refers to the degree of disorderliness of a system.
Ice Cube --> As the ice cube melts, it undergoes a change in state of matter from solid to liquid hence it's entropy increases as the degree of movement of its molecules is more disordered in the liquid state.
This means the likely options are; 1, 3 and 4.
Sidewalk --> The entropy here decreases as the ice melts on the side walk. This is because there is a reduction in temperature. Entropy is directly proportional to temperature. Decrease in temperature leads to decrease in entropy.
This means the likely option is 1 and 3
The net entropy change of the system is however positive.
what form of energy causes an ice cube to melt
A.mechanial
B.magnetic
C.sound
B.thermal
Answer:
Thermal
Explanation:
When something heats up its atoms become further apart making it melt when something heats up or gets heat or loses heat that's thermal energy
A solution has a pH of 11.75. Calculate the [H:0*] of the solution
The [H₃0⁺] of the solution : 1.778 x 10⁻¹² M
Further explanationpH is the degree of acidity of a solution that depends on the concentration of H⁺ ions. The greater the value the more acidic the solution and the smaller the pH.
pH = - log [H⁺]
So that the two quantities between pH and [H⁺] are inversely proportional because they are associated with negative values.
A solution whose value is different by n has a difference in the concentration of H⁺ ion of 10ⁿ.
pH of solution = 11.75
the [H₃0⁺] of the solution :
[tex]\tt pH=-log[H_3O^+]\\\\11.75=-log[H_3O^+]\\\\(H_3O^+]=10^{-11.75}=1.778\times 10^{-12}[/tex]
Percent yield is very important in terms of money. The higher the percent yield, the more of a product you can make. If you are working for a drug company and your theoretical yield is 120 kg, but you actually made 105 kg, what is your percent yield?
A. 8.75%
B. 114%
C. 87.50%
D. 15.00%
Answer:
87.5 %
Explanation:
Step 1: Given data
Theoretical yield: 120 kgReal yield: 105 kgStep 2: Calculate the percent yield
When working with chemical reactions, we can determine the efficience in obtaining a product measuring the percent yield. The theoretical yield is the maximum amount of product that we could obtain according to the stoichiometry, whereas the real yield is the amount of product that we actually obtain when we carry out the process. We can calculate the percent yield usign the following expression.
%yield = real yield / theoretical yield × 100%
%yield = 105 kg / 120 kg × 100%
%yield = 87.5 %
How much excess reactant remains from the reaction of 8.3g of sodium and 4.5g of chlorine?
a. 8.2g Na
b. 5.4g Na
c. 5.4g Cl2
d. 8.2g Cl2
Answer:
5.4 g Na
Explanation:
Calculate the mass of sodium chloride from both reactants. The lesser value is the amount is the theoretical yield. Subtract the mass of the calculated mass of sodium chloride from the mass of the reactants.
true or false the human body system works together to maintain
Answer:
Im pretty sure it would be true
Explanation:
A metal ion uses d2sp3 orbitals when forming a complex. What is its coordination number and the shape of the complex?
Answer:
Octahedral
Explanation:
The idea of hybridization is a valence bond concept introduced by Linus Pauling and soon became an important explanation for the structure of molecules even in coordination chemistry.
Hybridization involves the mixing of orbitals of appropriate energy to form a new set of orbitals that are more suitable for bonding with ligands.
When one s, two d and three p orbitals are hybridized in complex formation, octahedral complexes are formed.
Protons and neutrons are similar because they both:
cause objects to become charged
are attracted to electrons
are found in the nucleus of an atom
have positive charges
Answer:
C. are found in the nucleus of an atom
Explanation:
Protons and Neutrons are always located at the center of the atom also called as the nuclei of the atom and constitute nearly all the mass of the atom, while the electrons revolve around them in orbits called shells. Only protons have a positive charge and electrons have negative charges, due to which only protons and electrons attract each other, while neutrons lack charges or have 'Neutral Charges'.
Explain how atoms organize to create larger structures?
Answer:
First of all they are super tiny particles of neutrons, electrons and protons. Then they come together to organize a structure of atom. Atoms come together to form a molecule and smaller molecules work together to form macromolecules. Thus, how they organize and form building blocks of a substance.
Hope it helps!<3
Write the formula for diphosphorous pentoxide
Answer:
P4O10
Explanation:
What is the net ionic equation for the acid-base reaction between chlorous acid and sodium hydroxide?
Answer: [tex]HCO_2(aq)+OH^-(aq)\rightarrow ClO_2^-(aq)+H_2O(l)[/tex]
Explanation:
Neutralization is a chemical reaction in which an acid and a base reacts to form salt and water.
Spectator ions are defined as the ions which does not get involved in a chemical equation or they are ions which are found on both the sides of the chemical reaction present in ionic form.
The reaction of chlorous acid (weak acid) and sodium hydroxide (strong base) is written as:
[tex]HClO_2(aq)+NaOH(aq)\rightarrow NaClO_2(aq)+H_2O(l)[/tex]
The equation can be written in terms of ions as:
[tex]HClO_2(aq)+Na^+(aq)+OH^-(aq)\rightarrow Na^+(aq)+ClO_2^-(aq)+H_2O(l)[/tex]
The ions which are present on both the sides of the equation are sodium ions and hence are not involved in net ionic equation.
Hence, the net ionic equation is :
[tex]HCO_2(aq)+OH^-(aq)\rightarrow ClO_2^-(aq)+H_2O(l)[/tex]
What is the total charge of an iron nucleus
When forming an ion, nitrogen will have what charge?
Answer:
The valence electrons of nitrogen in its compounds are all sp³ hybridized orbitals. The formal charge on N is usually -1 for an anion, 0 for a neutral compound, and +1 in cations. A nitrogen atom with a formal charge of -3 would correspond to a nitride ion, N³⁻, which is strongly basic in aqueous solution. Hope this helps...
Explanation:
Brainliest please?
Rocks melt at what temperature range? a. 50 to 100 degrees Celsius b. 130 to 200 degrees Celsius c. 220 to 500 degrees Celsius d. 600 to 1,300 degrees Celsius
600 and 1,300 degrees Celsius
In pretty sure
Someone took the last cookie from the cookie jar last night. The last person to leave the scene is the culprit. Who was it? Highlight the guilty culprit based on the clues provided.
#1...TRUE/FALSE, the best way to write a conclusion is to use the RERUN method.?
#2...TRUE/FALSE, an example of an inference is “I saw it rain today.”?
#3...TRUE/FALSE, an example of a quantitative observation is “That is a red doll.”?
#4...TRUE/FALSE, a scientific hypothesis is written as “If [independent variable] Then [dependent variable.]”?
please answer all of them
A gas sample occupies 4.39 L at 44 ºC. What will be the new volume, using Charles’ Law, if the temperature decreases to 25 ºC?
Hi there! :)
[tex]\large\boxed{x = 2.49 L}[/tex]
Use the proportion for Charles' Law where:
[tex]\frac{v_{1}}{t_{1}}= \frac{v_{2}}{t_{2}}[/tex]
v1 = initial volume
t1 = initial temperature
v2 = final volume
v2 = final temperature
Substitute in the given values into the proportion:
v1 = 4.39 L
t1 = 44° C
t2 = 25°C
v2 = x L
Set up the proportion:
[tex]\frac{4.39}{44} = \frac{x}{25}[/tex]
Cross multiply:
[tex]25 * 4.39 = 44x\\\\109.75 = 44x\\\\x = 2.49 L[/tex]
Answer:
The new volume will be approximately 2.49 L.
Explanation:
We are given that a gas sample occupies 4.39 L at 44° C.
We are also given that we are going decrease the temperature to 25° C.
Charles' Law has a formula which shows the relationship between the volumes of a samples and the temperatures of the samples.
The proportion is shown as:
[tex]\displaystyle \bullet \ \ \ \frac{V_1}{T_1} = \frac{V_2}{T_2}[/tex],
where V₁ and V₂ are the initial and final volume respectively and T₁ and T₂ are the initial and final temperature respectively.
This proportion can be used to determine what our unknown is. We need to know the final volume.
[tex]\displaystyle \frac{4.39 \ \text{L}}{44 \ \text{C}} = \frac{\text{x}}{25 \ \text{C}}\\\\\\\frac{4.39}{44} = \frac{x}{25}\\\\\\4.39 \times 25 = 44 \times x\\\\\\44x = 109.75\\\\\\\frac{44x}{44}=\frac{109.75}{44}\\\\\\x = 2.49432 \approx \boxed{2.49 \ \text{L}}[/tex]
Therefore, if we reduce the temperature to 25 °C, we will be reducing the volume of the substance to 2.49 L.
Chemistry problem. please help
Answer:
solid X contains only ionic bond, and solid Y contains only covalent bonds.
Explanation:
solid X contains only ionic bond, and solid Y contains only covalent bonds. Because ionic compounds they have high melting point compared to covalent compounds, ionic compound they are generally insoluble in non polar solvent such as toluene but soluble in polar solvent such as water, ionic compound they conduct electricity.
If the resistance of a circuit is 3 ohms, and the voltage produced by the cell in the circuit is 12 volts, what's the magnitude of the current?
Answer:
4 AExplanation:
The magnitude of the current can be found by using the formula
[tex]i = \frac{v}{r} \\ [/tex]
v is the voltage
r is the resistance
From the question we have
[tex]i = \frac{12}{3} = 4 \\ [/tex]
We have the final answer as
4 AHope this helps you
Answer:
4A
Explanation:
How many joules are required to melt 250 grams of water
Answer:
i not sure but i searched it up and it said Q=104525J
Explanation:
Please answer. Thank you
Answer:
Explanation:
what are tho anwser choices
THE OH BOND IN WATER IS POLAR BECAUSE
Answer: In the case of water, we know that the O-H covalent bond is polar, due to the different electronegativities of hydrogen and oxygen. Since there are two O-H bonds in water, their bond dipoles will interact and may result in a molecular dipole which can be measured.
Explanation:
A sample of radioactive material starts with 80 grams. After 3 half-lives have passed, how much radioactive sample remains?
Answer:
After 3 half lives 10 g of radio active material left.
Explanation:
Given data:
Total amount of radio active material = 80 g
Amount left after 3 half lives = ?
Solution:
At time zero = 80 g
At first half life = 80 g/2 = 40 g
At 2nd half life = 40 g/2 = 20 g
At 3rd half life = 20 g/2 = 10 g
Thus, after 3 half lives 10 g of radio active material left.
Please help with the chart
Answer:
no
Explanation:
what is the molarity of a solution made by adding 0.720 mole of NaOH to 2.40 liters of water
Answer:
Molarity = 0.3 M
Explanation:
Given data:
Moles of NaOH = 0.720 mol
Volume of water = 2.40 L
Molarity = ?
Solution:
Molarity is used to describe the concentration of solution. It tells how many moles are dissolve in per litter of solution.
Formula:
Molarity = number of moles of solute / L of solution
Molarity = 0.720 mol / 2.40 L
Molarity = 0.3 mol/L
Molarity = 0.3 M
A sample of an unknown compound is vaporized at 150.°C . The gas produced has a volume of 960.mL at a pressure of 1.00atm , and it weighs 0.941g . Assuming the gas behaves as an ideal gas under these conditions, calculate the molar mass of the compound. Round your answer to 3 significant digits.
Answer:
the molar mass of the compound is 34.0 g /mol
Explanation:
The computation of the molar mass of the compound is as follows:
As we know that
PV = nRT
n = mass ÷ MW
PV = mRT ÷ MW
It can be rearrange as
MW = mRT ÷ (PV)
MW = (0.941)(0.082)(150 + 273) ÷ (1 × 0.96)
= 33.99g/mol
= 34.0 g /mol
Hence, the molar mass of the compound is 34.0 g /mol
