When two substances combine to form a mixture, the properties of the substances change. True False
Answer:
Tell students that sometimes when two (or more) substances are mixed together, a change occurs and another substance (or substances) is created. This is called a chemical reaction. Gas may form, heat may be produced, and color may change. These types of changes indicate that a chemical reaction has occurred.
Aside from invasives like the crown-of-thorns starfish, what other factor is killing the Great Barrier Reef?
O increased temperatures
O overactive algae
O reactive forms of oxygen
O coral bleaching
Answer:
increased temperatures
Explanation:
The temperatures are increasing in the ocean because of ocean warming, by climate change. The heat in the ocean stresses healthy corals, which drains them of their vibrant colors, known as bleaching.
HCl (aq) + H2O (l) ⇌ H3O^+ (aq) + Cl^- (aq)
In 1.0 M HCl (aq), is nearly 100 percent dissociated, as represented by the equation above. Which of the following best helps to explain why, in 0.01 M HCN (aq), less than 1 percent of HCN is dissociated?
A. Compared to the HCl (aq) solution, the concentration of the HCN (aq) solution is much too dilute to achieve 100 percent dissociation.
B. The CN^- ion is not very soluble in water, and a solid precipitate would form if more of the HCN dissociated..
C. The equilibrium constant for the dissociation of HCN (aq) is much smaller than that for the dissociation of HCl (aq).
D. HCN (aq) reacts with water to form a basic solution, and the high concentration of OH^- (aq) interferes with the dissociation process.
There is lesser dissociation of hydrogen cyanide as compared to HCl, as equilibrium constant for the dissociation of hydrogen cyanide has been smaller than HCl. Hence, option C is correct.
Hydrogen cyanide has been a weak acid that has been dissociated into the constituent ions. The dissociation of the compound in water has been corresponds to the equilibrium constant.
Equilibrium constant for hydrogen cyanide and HClThe equilibrium constant has been defined as the ratio of the concentration of solute and solvent ions at equilibrium.
The sample with lesser equilibrium constant tends to dissociate at lesser concentration as well.
The equilibrium constant for the dissociation of hydrogen cyanide has been smaller than HCl. Thus, there will be lesser dissociation of hydrogen cyanide as compared to HCl. Hence, option C is correct.
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What happens when an electron jumps from energy level 1 to energy level 2 in an atom?
The density of pentanol, C3H20, is 0.8110 g/mL. Calculate the volume occupied by 7.455 moles of pentanol. What is the volume occupied by 7.455 moles of pentanol?
The volume occupied by 7.455 moles of pentanol is 553.5 mL or 0.5535 L.
What does molar mass of a compound signify?The molar mass of a given compound is the mass of one mole of that compound. It is expressed in unit as grams per mole (g/mol).
To calculate the volume of pentanol occupied by 7.455 moles of the substance, we can use the following formula:
Volume = (number of moles x molar mass) / density
The molar mass of pentanol (C3H8O) can be calculated as:
3 x atomic mass of carbon (12.01 g/mol) = 36.03 g/mol 8 x atomic mass of hydrogen (1.01 g/mol) = 8.08 g/mol 1 x atomic mass of oxygen (16.00 g/mol) = 16.00 g/mol Total molar mass = 60.11 g/mol
Placing the given values into the formula, we get:
Volume = (7.455 mol x 60.11 g/mol) / 0.8110 g/mL Volume = 553.5 mL or 0.5535 L
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How many moles are in 8.30 X 1023 molecules of H2O? with the step
Answer:
Answer: 1.38 moles
Explanation: According to Avogadro's law, 1 mole of every substance contains Avogadro number of particles (atoms, molecules or ions) i.e.6.023*10^23 particles.
Given : 1 mole molecule of water contains 6.023*10^23 molecules of water.
6.023*10^23 molecules are present in = 1 mole
8.30*10^23molecules will be present in =
1/6.023*10^23 ×8.30*10^23=1.38 moles
Thus molecules is equal to 1.38 moles.
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An allergy medicine is usually stored in a cabinet at room termperature where its molecules move around each other. By
mistake, an intern transferred energy into the medicine. After one hour, the intern found the medicine and noticed that it
was a liquid. How were the molecules moving when the intern found the medicine? Explain why the molecules were
moving this way after the intern transferred energy ito the medicine.
Answer:
hello, can you pleas egive me the answer? i have the same exact question. thank you!
Explanation:
Trial 12 1.Volume of Acid used ( mL) 2020 2.Molarity of acid used (M) 0.0160.016 3.Initial volume reading of base buret 018.6 4.Final volume reading of base used 18.636.9 5.Volume of base used (4-3, mL) _________ _________ 6.Molarity of base (1*2/5, M) _________ _________ 7.Average molarity of base _________
Answer:
[tex]V_B = 18.3mL[/tex] -- Volume of base used
[tex]M_B = 0.0175M[/tex] --- Molarity of base
Explanation:
Given
[tex]V_A = 20mL[/tex] -- Volume of acid used
[tex]V_B_1 = 18.6mL[/tex] --- Buret Initial reading
[tex]V_B_2 = 36.9mL[/tex] --- Buret Final reading
[tex]M_A = 0.016M[/tex] --- Molarity of the acid
Solving (a): Volume of base used (VB)
This is calculated by subtracting the initial reading from the final reading of the base buret.
i.e.
[tex]V_B = V_B_2 - V_B_1[/tex]
[tex]V_B = 36.9mL - 18.6mL[/tex]
[tex]V_B = 18.3mL[/tex]
Solving (b): Molarity base (MB)
This is calculated using:
[tex]M_A * V_A = M_B * V_B[/tex]
Make MB the subject
[tex]M_B = \frac{M_A * V_A }{V_B}[/tex]
This gives:
[tex]M_B = \frac{0.016M *20mL}{18.3mL}[/tex]
[tex]M_B = \frac{0.016M *20}{18.3}[/tex]
[tex]M_B = \frac{0.32M}{18.3}[/tex]
[tex]M_B = 0.0175M[/tex]
Solving (c): There is no such thing as average molarity
A sample of polystyrene, which has a specific heat capacity of 1.880 J.g .°C , is put into a calorimeter (see sketch at right) that contains 300.0 g of water. The polystyrene sample starts off at 94.9 °C and the temperature of the water starts off at 22.0 When the temperature of the water stops changing it's 27.7 °C. The pressure remains constant at 1 atm. Calculate the mass of the polystyrene sample.
Answer:
56.6g
Explanation:
Given that :
Mass of water, m1= 300.0 g
Temperature of water, T1= 22°C
Specific heat capacity of water, C= 4.184 J/g°C
Mass of polystyrene, m2=?
Temperature of polystyrene = 94.9
Specific heat capacity of polystyrene, c2= 1.88 J/g°C
Final temperature = 27.7 oC
Heat lost by polystyrene = Heat gained by water
mc(dT) = mc(dT)
m2 * 1.88 * (94.9 - 27.7) = 300 * 4.184 * (27.7 - 22)
m2 * 1.88*67.2 = 300*4.184*5.7
126.336 * m2 = 7154.64
m2 = 7154.64 / 126.336
m2 = 56.631838
Hence, mass of polystyrene = 56.6g
On another planet, the isotopes of titanium have the given natural abundances.
Isotope Abundance
Mass (u)
46Ti
70.600%
45.95263
48Ti
12.900%
47.94795
50Ti
16.500%
49.94479
What is the average atomic mass of titanium on that planet?
Circuit A has a resistance of 7.5 ohms, and circuit B has a resistance of 5 ohms. Which statement about the circuits must be correct?
If the voltage of circuit A is equal to the voltage of circuit B, then the current in circuit A is equal to the current in circuit B
If the current in circuit A is equal to the current in circuit B, then the voltage in circuit A is less than the
voltage in circuit B
If the current in circuit A is less than the current in circuit B, then the voltage in circuit A is less than the
voltage in circuit B
If the voltage of circuit A is equal to the voltage of circuit B, then the current in circuit A is less than the
current in circuit B
Answer:
If the voltage of circuit A is equal to the voltage of circuit B, then the current in circuit A is less than the current in circuit B
Explanation:
To know the the correct answer to the question, do the following:
Case 1: Let the circuit A and B have equal voltage say 24 V.
For Circuit A:
Voltage (V) = 24 V
Resistance (R) = 7.5 ohms
Current (I) =?
V = IR
24 = I × 7.5
Divide both side by 7.5
I = 24 / 7.5
I = 3.2 A
For Circuit B:
Voltage (V) = 24 V
Resistance (R) = 5 ohms
Current (I) =?
V = IR
24 = I × 5
Divide both side by 5
I = 24 / 5
I = 4.8 A
Thus for the same voltage, current in circuit A is less than the current in B.
Case 2: Let circuit A and B have equal current say 2 A
For circuit A:
Current (I) = 2 A
Resistance (R) = 7.5 ohms
Voltage (V) =?
V = IR
V = 2 × 7.5
V = 15 V
For Circuit B:
Current (I) = 2 A
Resistance (R) = 5 ohms
Voltage (V) =?
V = IR
V = 2 × 5
V = 10 V
Thus, for the same current, the voltage in circuit A is greater than the voltage in B
Case 3: Let circuit A have a current of 4 A and circuit B have a current of 5 A
For circuit A:
Current (I) = 4 A
Resistance (R) = 7.5 ohms
Voltage (V) =?
V = IR
V = 4 × 7.5
V = 30 V
For circuit B:
Current (I) = 5 A
Resistance (R) = 5 ohms
Voltage (V) =?
V = IR
V = 5 × 5
V = 25 V
Thus, when the current in circuit A is less than the current in circuit B, the voltage in circuit A is greater than the voltage in circuit B.
From the illustrations above and the options given in the question, the current answer is:
If the voltage of circuit A is equal to the voltage of circuit B, then the current in circuit A is less than the current in circuit B
Question 10 of 35
A red blood cell can be used to model a typical animal cell.
What would happen to a red blood cell placed in very salty water?
O A. It would stay the same size because salt cannot cross the cell
membrane.
B. It would swell and burst as water moves into the cell, where there
is a higher concentration of water.
C. It would swell and burst because salt would be transported across
the cell membrane.
O D. It would shrink as water moves out of the cell to where there is a
lower concentration of water.
How many pounds of ice are required to absorb 4900 kJ of heat as the ice melts? The heat of fusion of water is 0.334 kJ/g.
help pls
Answer:
Q = ΔH fusion * mass (g)
when we have:
ΔH fusion (the heat (or enthalpy) of fusion = 0.334 kJ/g
and mass of ice = 22.4 g
so by substitution, we can get the energy (Q) required to melt this mass of ice:
∴ Q = 0.334KJ/g * 22.4 g
= 7.48 KJ
∴ the energy required to melt 22.4 g of ice is = 7.48 KJ
Explanation:
write the chemical equation of the reaction with a change in colour
Answer:
(i) Change in colour (ii) Change in temperature (iii) Formation of precipitate
Explanation:
(i) Change in colour: Reaction between lead nitrate solution and potassium iodide solution. Pb(NO3)2(aq)+2KI → PbI2(s)+2KNO3(aq) In this reaction, colour changes from colourless to yellow. (ii)Change in temperature: Action of dilute sulphuric acid on zinc. Zn(s) + H2SO4(aq) → ZnSO4(aq) + H2 In this reaction, heat is evolved (iii) Formation of precipitate: Action of barium chloride on sodium sulphate. BaCl2(aq) +Na2SO4(aq) → BaSO4(s) +2NaCl(aq) BaSO4(s)
Is a burning log an exothermic or endothermic event if the log is the (system) ?
Answer:
Exothermic Reaction
Explanation:
Burning wood in air is an exothermic process (it releases heat), but there is an energy barrier, so it requires a bit of heat in the beginning to get the reactions started.
Wood reacts with oxygen in the air to form (mostly) carbon dioxide and water vapor. The process involves many different individual chemical reactions, and it requires some energy to initiate the reactions. This is because it's usually necessary to break some chemical bonds (endothermic) before new stronger bonds can be formed (exothermic). Overall, though, more heat is released in forming the final products than is consumed in starting new reactions.
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In the given question, a burning log is an exothermic event if the log is the system.
An exothermic reaction releases energy to the surroundings, usually in the form of heat. The change in enthalpy is negative.
When a log burns, it reacts with oxygen in the air to produce carbon dioxide, water vapor, and heat. This heat is released to the surroundings, making the burning log an exothermic event.
Therefore, a burning log is an exothermic event if the log is the system. This is due to the fact that the reaction emits heat into the environment, making it an exothermic reaction.
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Given 5.86 grams of NaN3, how many grams of Na are produced?
Answer:
what no entiendo nada jahag6
When 5.86 grams of NaN3, then 22.99 gram of Na are produced by using mole formula.
What is gram ?A thousandth of a kilo-gram in terms of mass in the metric system.
What is mole?A mole is a unit of measurement for atom amount. A mole of Iron atoms weighs heavier than just a mole of Carbon molecules because it is measured by the number of atoms present instead of by weight.
The reaction can be written as:
[tex]2 Na N_{3}[/tex] → 2Na + [tex]3N_{3}[/tex].
It can be seen that 2 mole of sodium azide give 3 mole of nitrogen molecule.
Calculate the moles of Na.
Moles of Na = 1 mol sodium azide × 2 mol of Na / 2 mol sodium azide = 1 mole of Na.
Calculate the mass of Na.
Mass of Na = 1 mol Na × 22.99 g Na / 1 mol Na = 22.99 gNa.
Therefore, the mass of Na will be 22.99 gram
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20 Points!! Which of the following is a synthesis reaction? AgNO3+NaCI--> AgCI+NaNO3
CH4+O2->CO2+H2O SO3+H2O-> H2SO4 Cu+AgNO3 ->Ag+CuNO3
What kind of questions do scientists ask?
A. Ones that there are no right answers to
B. Ones that only deal with scientific issues
C. Ones that deal with matters of opinion
D. Ones that are answered through observing
ones that are answered through observing :)
Answer: D.
Explanation:
ones that are answered through observing.
If two-parent with AB blood group claim and say that they have a baby with O blood group is born to them and it is their own baby and not adopted. Do you think they are speaking the truth?
who knows this answer
Which of the following can be calculated from the mass of the reactants used in a chemical reaction? (Select all that apply)
Theoretical yield of products
Amount of limiting reactant used in a reaction
Actual yield of products
Amount of excess reactant from a reaction
Answer:
Can you explain it more please
Explanation:
Glucose is the monomer in the natural polymers ____________________ and cellulose.
Answer:
Starch
I hope this helps
How many atoms are in 12 moles of sodium?
Answer: There are 1.20 x 1024 atoms of sodium in 2 moles
Explanation:
Mass of hydrated copper sulfate in CuSo4.5H2O
Answer: Molar mass of [tex]CuSO_4.5H_2O[/tex] is 249.68 g/mol.
Explanation:
Molar mass is the mass of 1 mole of the molecule. It is calculated by adding masses of all the atoms in the given molecule.
[tex]CuSO_4.5H_2O[/tex] contains one atom of copper , 1 atom of sulphur, 9 atoms of oxygen and 10 atoms of hydrogen
Mass of copper = 63.5 g/mol
Mass of sulphur = 32.06 g/mol
mass of oxygen = 16.00 g/mol
Mass of hydrogen = 1.008 g/mol
Thus mass of [tex]CuSO_4.5H_2O[/tex] = 63.5(1)+32.06(1)+16.00(9)+1.008(10)=249.68 g
Molar mass of [tex]CuSO_4.5H_2O[/tex] is 249.68 g/mol.
What is the correct name for Cr2O3?
A. Chromium trioxide
B. Chromium(III) oxide
C. Dichromium trioxide
D. Chromium(II) trioxide
kylie jenner wants to test if red or pink lipstick makes her lips look bigger. what is the independent variable here?
Answer:
her ugly duck lips
Explanation:
Answer:
her lips.
Explanation:
the dependent variable is the lip stick because it changes but her lips do not actually change at all, ......i think. ;)
Which of the following sentences uses commas correctly?
-----------------------------------------------------------------------------------------------------------------------------
I got all of the answers on the test correct, didn't I?
I, got all of the answers on the test correct didn't I?
I got all of the answers, on the test correct didn't I?
I got all of the answers on the test, correct didn't I?
To run a spectrophotometry experiment, begin by _________ the spectrophotometer and preparing the samples. Be sure to select the correct ________, then run a measurement on the _________ solution. Follow up by running measurements on _______solutions. Once data is collected, turn off the instrument, clean the area, and discard the samples.
Answer:
To run a spectrophotometry experiment, begin by warming up the spectrophotometer and preparing the samples. Be sure to select the correct wavelength, then run a measurement on the blank solution. Follow up by running measurements on sample solutions. Once data is collected, turn off the instrument, clean the area, and discard the samples.
Explanation:
The spectrophotometer is a device used in laboratories to carry out analysis in experiments that need to measure and compare the amount of light absorbed or transmitted between samples, regardless of whether the samples are transparent or opaque solid. The spectrophotometer can be single-beam and double-beam. Regardless of the nature of the beam, to perform a spectrophotometry experiment, you must start by heating the spectrophotometer and preparing the samples. Make sure to select the correct wavelength and perform a measurement on the blank solution. Follow up by performing measurements on sample solutions. Once the data is collected, turn off the instrument, clean the area and discard the samples.
mineral and nutrient solution is in water epiphyte plants or hydroponic plants
Answer:
hydro ponic plants
Explanation:
coz they are hydro
How does a temperature increase cause the rate of a reaction to increase?
A. It increases the kinetic energy of the molecules.
B. It decreases orientation requirements of the molecules.
C. It increases the equilibrium constant for the reaction.
D. It decreases the activation energy of the reaction.
Answer:
B
Explanation:
"The temperature increases cause the rate of a reaction to increases the kinetic energy"
What is rate of reaction?
The reaction rate, also known as the rate of reaction, is the rate for which a chemical reaction occurs, and is proportional to increase in product concentration per unit time and the reduction in reactant concentration per unit time. The rate of reaction varies greatly.
What is kinetic energy?
An object's kinetic energy is the energy it has as a result of its motion. It is the amount of work required to push a body of a given mass from rest to a certain velocity. The body keeps its kinetic energy gained during acceleration unless that speed changes.
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nitrophenol is more acidic than phenol.
Answer:
The p- nitrophenol is more acidic than phenol because the deactivating nature of nitro group and after loosing the protons it makes more resonance stabilization as nitro group is having strong deactivating nature so it attracts electrons towards it.
