A student performs an experiment in which 5.0 g of potassium chloride, KCI, are dissolved into 100.0 mL of distilled water. The student records the
temperature both before and after dissolving the KCl into the water, as shown in the data table below. Use this data to answer the question that follows.
Initial Temperature, °C Final Temperature, °C
21.8°C
16.4°C
Which statement below is a correct conclusion based on these results ?
The temperature of the water decreases and so the reaction is exothermic
The temperature of the water increases and so the reaction is exothermic
The temperature of the water decreases and so the reaction is endothermic
The temperature of the water increases and so the reaction is endothermic
Answer:
The temperature of the water decreases and so the reaction is endothermic
Explanation:
This option is correct because when the 5.0g potassium chloride (KCl) was added to the 100.0ml distilled water, the KCl made the water absorb heat coming from it which made the water decrease in temperature thereby causing an endothermic reaction.
An endothermic reaction actually takes place when the temperature of a system which is isolated decreases. The surroundings of a non-isolated system actually gains heat. While in an exothermic reaction, the temperature of a system increases due to the release or evolution of heat. This heat is released into the surroundings.
What is the hydroxide concentration of a solution with a poH of 2? Is this solution acidic, basic or neutral?
fireworks convert chemical energy into what kind of energy
Answer:
Kinetic energy
Explanation:
Fireworks convert chemical energy into kinetic energy to send them flying upward. Hope it is correct!
plz help ❤️
Explain how the pH of water has a synergistic relationship with other substances.
Provide an example.
Answer:
Explanation:
he pH of the water will determine the toxic effects, if any, of these substances.
Pure water is neutral with the pH of 7. But when water combines with other substance the pH varies as per the acidity of the combining substance.
What is pH?pH is the measure of acidity of a solution and mathematically it is the negative logarithm of hydrogen ion concentration. Acidic substance have a pH of less than 7 whereas, basic substance have higher pH value.
Water when combines with some acids, its acidity increases. For example acid rain resulting from the reaction of rain water with oxides of nitrogen and Sulphur forming nitric acid and sulphuric acid.
pH of water have a role in the toxic effects of components in water pH and alkalinity of water determines the coagulation of other substances in water.
Hence, the properties of other substance in water is pH dependent and might effect the alkalinity or acidity of water as well the properties of substances in water such as toxicity.
To learn more about pH , refer the link below:
https://brainly.com/question/2288405
#SPJ2
raw material for fusion
Answer:
Deuterium and Lithium.
Explanation:
I searched it up on google.
Which units can be used to describe the thermal
energy within a substance?
Answer: Btu, British Thermal Unit is used to express thermal energy when working in pounds and degrees Farenheit.
Calories are used when working in grams and degrees Centigrade or Kelvin (SI units)
A Joule is the British system unit used to measure heat transfer.
Explanation:
Please help me it’s due today
Answer:
I think it is A. the two forces are equal, or balanced, neither the table nor the book moves up or down.
Explanation:
Tome, the other options don’t make no sense
Perform the arithmic shown AND round your answers to the correct number of significant digits.
56.5in + 95.3in + 15 in
(Fill in the blank)
Answer:
167in
Explanation:
Given arithmetic;
56.5in + 95.3in + 15in
To determine the correct significant digits, the sum cannot be more precise than the least precise value in the addition;
The least precise is 15in and it is in 2significant places;
56.5in
95.3in
+ 15 in
......................
166.8in
......................
The value is 167in
Calculate the concentration (M) of arsenic acid (H3AsO4) in a solution if 25.00 mL of that solution required 35.21 mL of 0.1894 M KOH for neutralization.
Answer:
[tex]M_{acid}=0.08892M[/tex]
Explanation:
Hello!
In this case, since the reaction between arsenic acid and potassium hydroxide is:
[tex]H_3AsO_4+3KOH\rightarrow K_3AsO_4+3H_2O[/tex]
Thus, since the mole ratio between the acid and the base is 1:3, at the equivalence point we can write:
[tex]3n_{acid}=n_{base}[/tex]
That in terms of molarities and volumes is:
[tex]3M_{acid}V_{acid}=M_{base}V_{base}[/tex]
Thus, the concentration of the arsenic acid is:
[tex]M_{acid}=\frac{M_{base}V_{base}}{3V_{acid}}=\frac{0.1894M*35.21mL}{3*25.00mL} \\\\M_{acid}=0.08892M[/tex]
Best regards!
The concentration (M) of arsenic acid in a solution of 25.00 mL is 0.088M.
How we calculate the molarity?Molarity of any solution will be calculated as:
M = n/V, where
V = volume
n is the moles and it will be calculated as:
n = W/M, where
W = given mass
M = molar mass
Given chemical reaction is:
H₃AsO₄ + 3KOH → K₃AsO₄ + 3H₂O
Moles of 35.21 mL of 0.1894 M KOH will be calculated as:
n = (0.1894)(0.035) = 0.0066 moles
From the stoichiometry of the reaction it is clear that:
1 mole of H₃AsO₄ = react with 3 moles of KOH
0.0066 moles of KOH = react with 1/3×0.0066= 0.0022 moles of H₃AsO₄
Now we calculate the molarity of H₃AsO₄ in 25mL of solution as:
M = 0.0022/0.025 = 0.088 M
Hence, required molarity is 0.088 M.
To know more about molarity, visit the below link:
https://brainly.com/question/26873446
Select the best answer from the choices below. Light has many properties of waves, but sometimes it also behaves like:
Answer:
A photon
Explanation:
When electrons pass close to the standing wave of light, they hit the particles that are called photons
Calculate Kb for a 0.1 M solution of cyanide ion, given that Ka for hydrocyanic acid is 6.2 x 10â10.a) 8.4 x 10â9b) 7.87 x 10â3c) 1.34 x 10â3d) 1.8 x 105e) 7.87 x 10â6f) 1.61 x 10â5g) 7.4 x 10â8
Answer:
Kb = 1.6 × 10⁻⁵
Explanation:
Step 1: Given data
Acid dissociation constant of hydrocyanic acid (Ka): 6.2 × 10⁻¹⁰
Concentration of cyanide ion (Cb): 0.1 M
Step 2: Calculate the basic dissociation constant (Kb) of cyanide ion
We have the Ka of HCN. We can calculate the Kb of its conjugate base using the following expression.
Ka × Kb = Kw = 1.0 × 10⁻¹⁴
Kb = 1.0 × 10⁻¹⁴/Ka
Kb = 1.0 × 10⁻¹⁴/6.2 × 10⁻¹⁰
Kb = 1.6 × 10⁻⁵
The Kb for a 0.1 M solution of cyanide ion is :
- 1.6 × 10⁻⁵
Base dissociation constantGiven:
Acid dissociation constant of hydrocyanic acid (Ka)= 6.2 × 10⁻¹⁰
Concentration of cyanide ion (Cb)= 0.1 M
Base dissociation constant (kb)=?
Ka × Kb = Kw = 1.0 × 10⁻¹⁴
Kb = 1.0 × 10⁻¹⁴/Ka
Kb = 1.0 × 10⁻¹⁴/6.2 × 10⁻¹⁰
Kb = 1.6 × 10⁻⁵
Learn more about " Kb":
https://brainly.com/question/26871012?referrer=searchResults
A sample of neon gas occupies 5.5 liters at 20°C and 650 mmHg. What is the expected volume of the gas at S.T.P.
Answer:
V₂ = 4.4 L
Explanation:
Given data:
Initial volume = 5.5 L
Initial pressure = 650 mmHg (650/760 =0.86 atm)
Initial temperature = 20 °C (20 +273 = 293 K)
Final temperature = 273 K
Final volume = ?
Final pressure = 1 atm
Solution:
Formula:
P₁V₁/T₁ = P₂V₂/T₂
V₂ = P₁V₁T₂/T₁ P₂
V₂ = 0.86 atm× 5.5 L × 273 K / 293 k × 1 atm
V₂ = 1291.29 atm.K.L / 293 k.atm
V₂ = 4.4 L
The balanced equation for the combustion of Hydrogen is:
2 H2 + O2 → 2H2O
How many moles of H2O will be formed from the complete reaction of 0.750 moles of O2?
0.375 mol
1.50 mol
2.67 mol
0.750 mol
Answer:
1.5 moles H₂O
General Formulas and Concepts:
Chemistry - Stoichiometry
Using Dimensional AnalysisExplanation:
Step 1: Define
RxN: 2H₂ + O₂ → 2H₂O
Given: 0.750 moles O₂
Step 2: Stoich
[tex]0.750 \ mol \ O_2(\frac{2 \ mol \ H_2O}{1 \ mol \ O_2} )[/tex] = 1.5 moles H₂O
Step 3: Check
We are given 3 sig figs.
Since our answer is 2 sig figs, we don't need to round.
How many moles of CO are produced when 1.8 moles C reacts?
Express your answer using two significat figures.
5C(s) + 2SO2(g) => CS2(l) +4CO(g)
Answer:
1.44mole of CO
Explanation:
The reaction equation is given as:
5C + 2SO₂ → CS₂ + 4CO
We check to see if the expression is balanced and it is so;
Now;
Given;
1.8mole of C reacted; how many moles of CO are produced;
From the balanced reaction equation:
5 mole of C is expected to produce 4 mole of CO
1.8 mole of C will then produce [tex]\frac{4 x 1.8}{5}[/tex] = 1.44mole of CO
Which of the following are fair conductors and are always solid at room temperature?
1.Metals
2.Nonmetals
3.Metalloids
4.Ions
Answer:
Metalloids and ions
Explanation:
Mercury is not solid at room temperature. (Metals)
Many nonmetals aren't good at conducting electricity. Oxygen for example. (Nonmetals)
Metalloids are always solid at room temp and are fair conductors. (Metalloids)
Ions are same as metalloids. (Ions)
PLS GIVE BRAINLIEST
Chem Muti Choice. Tell me the correct answer.
Answer:
my gues is red not a 100% but its in the 700s
Explanation:
In the image below if the frisbee represents lights, what does the fence represent?
Answer:
The atmosphere
Explanation:
It reflects and traps the light outside of the Earth's Atmosphere?
I think, hope i helped.
Calculate the following quantity: volume of 1.58 M calcium chloride that must be diluted with water
to prepare 994 mL of a 6.20 x 10^-2 M chloride ion solution.
what is the iupac name of CH3-CH2CH(CH3)CH2-COOH
Answer:
Butanoic acid.
Explanation:
Write two sentences explaining how the illustration and student observations support the cell theory?
Answer:
The classical cell theory was proposed by Theodor Schwann in 1839. There are three parts to this theory.
Explanation:
If Phosphorus, P, gained 3 electrons, the net ion charge would be
+5
-5
+3
-3
Answer:
-3
Explanation:
Phosphorus becomes phosphide with a -3 charge
PLZ HELP ME NO WRONG ANSWERS
Answer:
okay I will help you just message me johnpatrick on messenger
A buffer solution contains 0.0200 M acetic acid and 0.0200 M sodium acetate. What is the pH after 2.0 mmol of NaOH are added to 1.00 L of this buffer? pKa = 4.75 for acetic acid.
Answer:
The correct answer is 4.84
Explanation:
We use the Henderson Hasselbach's equation to calculate the pH of a buffer solution:
pH = pKa = log ( [conjugate base]/[weak acid])
In this case:
conjugate base: acetate ⇒ [conjugate base] = [acetate] = 0.0200 M
weak acid: acetic acid ⇒ [weak acid] = [acetic acid] = 0,0200 M
pH = pKa + log ([acetate]/[acetic acid])= pKa + log (0.0200 M/0.0200 M)
When a strong base- such as NaOH- is added, the acid reacts with OH⁻ to form the conjugate base. So, the conjugate base is increased while the acid is decreased. Thus, in 1 liter of solution we have:
acetate = (0,0200 mol/L x 1 L) + (2.0 mmol x 1 mol/1000 mmol) = 0.022 mol
acetic acid= (0,0200 mol/L x 1 L) - (2.0 mmol x 1 mol/1000 mmol) = 0.018 mol
Finally, we calculate the pH:
pH = 4.75 + log (0.022 mol /0.018 mol )= 4.84
Buffer has been the solution that resists the change in the pH of the solution with the addition of acid or base. The pH of buffer with NaOH has been 4.84.
What is pH?The pH has been the hydrogen ion concentration in the solution. The pH has been equivalent to pKa and can be given as:
[tex]\rm pka=log\dfrac{[base]}{[acid]}[/tex]
The base in the buffer has been the acetate, while acetic acid act as the acid.
The concentration of NaOH added to the solution has been given as:
[tex]\rm Molarity=\dfrac{moles}{volume}\\\\ NaOH=\dfrac{0.002\;mol}{1\;L}\\\\ NaOH=0.002\;M[/tex]
The addition of NaOH adds the concentration of base, and neutralization reduces the concentration of acid. Thus, the new pKa can be given as:
[tex]\rm pKa=log\dfrac{0.2+0.002}{0.2-0.002} \\pKa=log\dfrac{0.022}{0.018}[/tex]
The new pH of the solution has been the sum of the old and the new pKa value.
Thus, the pH of the new buffer has been given as:
[tex]\rm pH=4.75+log\dfrac{0.022}{0.018}\\ pH=4.84[/tex]
The pH of buffer with NaOH has been 4.84.
Learn more about buffer, here:
https://brainly.com/question/1423164
1.For Structure B the bond between carbon and sulfur is polar or non polar
2. Explain you’re answer
Answer:
polar
Explanation:
because carbon and sulfur have different electronegativities, the S=C bond is polar.
The entire molecule is nonpolar however because the dipoles (polar bonds) cancel out due to the geometry of the molecule (linear)
X-rays are often used in medical settings to create images of the body's internal structures such as bones. This is made possible by the
fact that X-rays are able to pass through the body's softer tissues without being absorbed.
Radio waves are also able to pass through the body's softer tissues without being absorbed. Why are radio waves not used to generate
medical images?
OA. The electrons in most atoms are not in high enough energy states to absorb the photons of radio waves.
OB. Radio waves tend to bend too much when they encounter solid materials to be used for generating accurate images,
OC
The frequency of most radio waves is too low to allow them to pass through bones or other solid materials.
OD.
Radio waves carry so little energy that they tend to pass through most atoms without an interaction taking place.
Answer:D
Explanation:I did it on study island.
Radio waves are not used to generate medical images because as per the electromagnetic spectrum ,the radio waves carry little energy that they pass through most atoms without interaction.
What is an electromagnetic spectrum?The electromagnetic spectrum consists of radiation which consists of waves made up of electromagnetic field which are capable of propogating through space and carry the radiant electromagnetic energy.
The radiation are composed of electromagnetic waves which are synchronized oscillations of electric and magnetic fields . They are created due to change which is periodic in electric as well as magnetic fields.
In vacuum ,all the electromagnetic waves travel at the same speed that is with the speed of air.The position of an electromagnetic wave in an electromagnetic spectrum is characterized by it's frequency or wavelength.They are emitted by electrically charged particles which undergo acceleration and subsequently interact with other charged particles.
Learn more about electromagnetic spectrum,here:
https://brainly.com/question/15576247
#SPJ2
A solution of NaF is added dropwise to a solution that is 0.0173 M in Ba 2. When the concentration of F- exceeds___M BaF2 will precipiate. Neglect volume changes. For BaF2
Answer:
0.0099M = [F⁻]
Explanation:
For BaF2, Ksp = 1.7x10⁻⁶
When BaF₂ is in solution, the equilibrium between the solid and the dissociated ions occurs as follows:
BaF₂(s) ⇄ Ba²⁺(aq) + 2F⁻(aq)
Where Ksp = 1.7x10⁻⁶ is defined as:
1.7x10⁻⁶ = [Ba²⁺] [F⁻]²
Where [] are equilibrium concentrations of each ion in solution.
That means you will add F⁻ until its concentration exceeds:
1.7x10⁻⁶ = [0.0173] [F⁻]²
9.827x10⁻⁵ = [F⁻]²
0.0099M = [F⁻]When more F⁻ is added, BaF₂ begins its precipitation.
Name and write one polyatomic ion with its charge.
Answer:
Because these ions contain more than one atom, they are called polyatomic ions. Polyatomic ions have characteristic formulas, names, and charges that should be memorized. For example, NO3− is the nitrate ion; it has one nitrogen atom and three oxygen atoms and an overall 1− charge.
Polyatomic Ions.
Name Formula
sulfite ion SO32−
Explanation:
Choose ALL the answers that apply.
Sound _____.
travels in transverse waves
requires a medium to travel through
travels most slowly through solids
speeds up when temperature is increased
is changed into electrical impulses by the cochlea
Answer:
Speeds up when temperature is increased and can travel through a solid
Explanation:
What is the ratio of potassium atoms to oxygen atoms in potassium oxide (K2O)?
K20
K = 1+
0 = 2-
K/0 = 1/2
the answer is K:O = 1:2
How many neutrons does the isotope of hydrogen called
deuterium have?
a. four
b. three
C. one
d. two