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Related Questions
Al wonders if adding salt to water will affect how long it takes the water to
freeze. Al thinks that salt water will freeze more quickly than fresh water.
He decides to check his hypothesis by conducting an experiment. Al takes
two ice trays and fills one with distilled water and the other with distilled
water that has two tablespoons of salt added. He makes sure he puts
exactly the same amount of water in each ice tray. Al takes the trays and
puts them side by side in the freezer. Al checks the ice trays every 10
minutes to see if the water in each tray has begun to freeze. Al finds that
after 20 minutes the water in the ice tray without the salt has started to
form ice, while the ice tray with the salt water is still completely liquid.
Ku
Answers
The hypothesis is that salt water freezes faster than fresh water.
The dependent variable is time taken for ice to appear.
The independent variable is presence or absence of salt
The constants are the amount of water in each tray, freezing conditions and length of time of exposure to freezing condition.
The control group is the tray to which salt was not added
The experimental group is the tray to which salt was added
The presence of solutes in a solution causes the freezing point depression.
A solution is made up of a solute and a solvent. In the presence of a solute, the freezing point of a pure solvent is decreased. This is because freezing point is a colligative property.
Colligative properties depend on the amount of solute present.
Hence, the pure water freezes faster (ice begin to appear earlier) than the salt water.
The hypothesis put forward in this experiment was found to be invalid by the experiment.
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Define physical and chemical properties, provide three examples of each, discuss their reversibility, and explain the fundamental differences between them.
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Answer:
Physical properties are defined as the properties which can be observed without changing its chemical composition.
For example: color, volume, and molecular weight.
Chemical properties are defined as the properties which can be observed only after changing chemical identity of the substance.
For example: reactivity, toxicity, and flammability.
The fundamental differences between physical and chemical properties are as follows:
Chemical properties are related to chemical bonds of the substance while physical properties are not.In chemical properties, chemical identity of substance changes while physical properties do not have any change.Chemical properties predict the reaction of substance while physical properties only describe the appearance of the substance.
Answer:
Chemical properties are related to chemical bonds of the substance while physical properties are not.
In chemical properties, chemical identity of substance changes while physical properties do not have any change.
Chemical properties predict the reaction of substance while physical properties only describe the appearance of the substance.
Explanation:
As the mass of the nucleus increases, what happens to the ratio of neutrons to protons in stable isotopes? A. The neutron:proton ratio decreases. B. The neutron:proton ratio increases. C. The neutron:proton ratio remains 1:1. D. The neutron:proton ratio remains 1.5:1.
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What combination of substances will give a buffered solution that has a pH of 5.05? (Assume each pair of substances is dissolved in 5.0 L of water.) (Kb for NH3 = 1.8 ´ 10–5; Kb for C5H5N = 1.7 ´ 10–9) Select one: a. 1.0 mole NH3 and 1.5 mole NH4Cl b. 1.5 mole NH3 and 1.0 mole NH4Cl c. 1.0 mole C5H5N and 1.5 mole C5H5NHCl d. 1.5 mole C5H5N and 1.0 mole C5H5NHCl e. none of these
Answers
Answer:
c. 1.0 mole C5H5N and 1.5 mole C5H5NHCl
Explanation:
We can determine pH of a buffer using H-H equation:
pH = pKa + log [A⁻] / [HA]
Where [A⁻] is concentration of conjugate base and [HA] concentration of weak acid. These concentrations can be computed as moles of each species.
We need to determine pKa of both NH₃ and C₅H₅N buffers, thus:
pKb = -log Kb
NH₃ pKb = -log 1.8x10⁻⁵ = 4.74
C₅H₅N pKb = -log 1.7x10⁻⁹ = 8.77
And pKa = 14 - pKb:
NH₃ pKa = 14 - 4.74 = 9.26
C₅H₅N pKb = 14 - 8.77 = 5.23
A buffer works only under pH's between pKa-1 and pKa + 1. As pKa NH₃ buffer is 9.23 is not possible to produce a buffer with pH 5.05 for this system.
Thus, we only will compute the buffers made with C₅H₅N:
c. 1.0 mole C5H5N (Weak base) and 1.5 mole C5H5NHCl (Conjugate acid)
pH = pKa + log [A⁻] / [HA]
pH = 5.23+ log [1.0 moles] / 1.5 moles]
pH = 5.05d. 1.5 mole C5H5N and 1.0 mole C5H5NHCl
pH = pKa + log [A⁻] / [HA]
pH = 5.23+ log [1.5 moles] / 1.0 moles]
pH = 5.41Right solution is:
c. 1.0 mole C5H5N and 1.5 mole C5H5NHClThe law of conservation of energy states that A: energy is always created and destroyed B: energy cannot be created or destroyed C: energy is unable to change forms D: energy should be saved as often as possible
Answers
Answer:
B
Explanation:
This is the First Law of Thermodynamics which states that energy cannot be created or destroyed.
what’s the answer to this?
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What is the molecular formula?Write down the molecular formula of the given compounds.
i. Calcium Sulphate
ii. Sodium Carbonate
iii. Water
iv. Carbon Dioxide
v. Potassium Nitrate
vi. Ammonium Chloride
Answers
Answer:
A molecular formula consists of the chemical symbols for the constituent elements followed by numeric subscripts describing the number of atoms of each element present in the molecule.
The molecular formula of the given compounds are:
CaSO4Na₂CO₃H2OCO2KNO3NH4ClWhat wavelength measures
A. Depth
B. Distance
C. Energy
D. Speed
E. Time
F. Volume
Answers
Answer:
Distance.
Explanation:
Wavelength (λ) can be defined as the distance between two successive crest or trough of a wave.
From the above definition, wavelength (λ) simply measures distance.
This can further be explained by obtaining the unit of measurement for wavelength (λ).
This can be illustrated below:
Wavelength is related velocity and frequency according to the following equation:
Velocity (v) = wavelength (λ) x frequency (f)
v = λf
λ = v/f
Velocity is measured in ms¯¹
Frequency is measured in hertz, Hz (s¯¹)
λ = v/f
λ = ms¯¹ / s¯¹
λ = m
We can see that wavelength is measured in metre (m) which is the same unit for measuring distance.
Therefore, wavelength measures distance.
you just got home from a run on a hot Atlanta afternoon. you grab a 1.00-liter bottle of water and drink three-quarters of it in one swig. How many moles of water did you consume?
Answers
Answer:
41.67 mol
Explanation:
1 Litre of water = 1000g
Mole = mass / molar mass
Mass of 1 L of water = 1000 g
Molar mass of water (H2O) :
(H = 1, O = 16)
H2O = (1 * 2) + 16 = (2 + 16) = 18g/mol
Amount of water consumed = (3/4) of 1 litre
= (3/4) * 1000g
= 750g
Therefore mass of water consumed = 750g
Mole = 750g / 18g/mol
Mole of water consumed = 41.6666
= 41.67 mol
The pH of a solution decreases by 2.0. How does the hydronium ion concentration of the solution change? Increases to 2 times the original concentration increases to 100 times the original concentration decreases to one one hundredth. Of the original concentration decreases to one half. Of the original concentration
Answers
Answer:
The hydronium ion concentration increases to 100 times the original concentration
Explanation:
The pH of a solution is defined as the negative logarithm of the hydrogen or hydronium ion concentration of that solution. It is given by the expression below:
pH = -log[H₃O⁺] = log[H₃O⁺]⁻¹
Assuming the solution was at neutral with original pH = 7;
The new pH of the solution will be = 7 - 2 = 5
At pH = 7;
log[H₃O⁺]⁻¹ = 7
[H₃O⁺]⁻¹ = 10⁷
[H₃O⁺] = 10⁻⁷
At pH = 5
log[H₃O⁺]⁻¹ = 5
[H₃O⁺]⁻¹ = 10⁵
[H₃O⁺] = 10⁻⁵
10⁻⁵ = 10⁻⁷ * 10²
But 10² = 100
Therefore, the hydronium ion concentration increases to 100 times the original concentration
Answer:
B
Explanation:
On Edge
0.024 is how many significant figures?
Answers
Answer:
24×10^-3Explanation:
[tex]Move \: the\:decimal \:point\:,\\3 \:times\:to\:the \:right = 24\\\\When \:the\:decimal\:point \: moves\\\:to\:the \:right\:it\:becomes\:a \:negative\:power\\\\0.024= 24 \times 10^-^3[/tex]
Answer the following questions based on the above graph(Electron affinity vs Atomic no.)
i)Why on moving from Li to Be, the value of electron gain enthalpy drops.
ii)Cl has a higher peak than fluorine. Explain.
iii)Why Fluorine has the highest value among its period members.
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i) Be has a fully filled 2s level.
ii) This is because chlorine is larger than fluorine.
iii) Fluorine needs only one electron to attain the octet configuration.
Electron affinity is the ability of an electron to accept gaseous electrons to yield gaseous ions with a negative charge.
Electron affinity depends on the size of an atom. Larger atoms have a higher electron affinity because they are better able to accept electrons.
The drop between Li and Be is because the 2s orbital in Be is already fully filled while Li has incompletely filled 2s level. electrons do not easily go into the higher energy 2p level.
The higher peak of chlorine is because chlorine is larger than fluorine hence the electron affinity of fluorine is less than that of chlorine. The smaller the ion the lesser the electron affinity.
Fluorine has the highest electron affinity in period 2 because it needs only one electron to attain the octet structure.
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What are half reaction
Answers
Answer:
When you don't have a complete reaction.
Explanation:
Happens a lot between a solvent and a solute. The solute may not bind well with the solvent I.e. water.
the part of the reaction involving oxidation or reduction
Sodium hydroxide and water will react at room temperature. What does this indicate about its activation energy? A. The activation energy is very low. B. The activation energy is at exactly 600 kJ. C. The activation energy is very high. D. The reaction cannot reach activation energy.
Answers
Answer:
The answer would be C.
Explanation:
I took a test with the same question.
The activation energy is very high. Hence, option C is correct.
What is activation energy?Activation energy is the sufficient amount of energy necessary to initiate a chemical reaction.
When sodium hydroxide (NaOH) dissolves in water, it is distributed into positively-charged sodium ions and negatively - charged hydroxide ions.
These cations and anions move around in the water, free and independent of each other, though cations tend to be surrounded more closely by anions and vice versa.
Hence, when sodium hydroxide and water will react at room temperature, the activation energy is very high.
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A student made the Lewis dot diagram of a compound as shown. Mg is written with two dots shown on its top. Cl is written on the right side of Mg. Cl has seven dots around it. An arrow is shown from one dot on Mg toward the vacant space around Cl. Another arrow is shown from the other dot on Mg toward the vacant space around Cl. On the top, the art title is written as Students Lewis Dot Model. What is the error in the Lewis dot diagram?
Answers
Answer:
The dots were not properly located and arrows are not used in Lewis structures
Explanation:
If we intend to write a Lewis structure for a compound, that lewis structure must consist of only dots. These dots actually show the valence electrons on the outermost shell of the molecule.
We do not involve arrows when writing dot electron structures for compounds. The valence electrons of magnesium ought not to be written together because they are not a lone pair, rather they are two unpaired electrons. The use of an arrow suggests a coordinate covalent bond which is not the case here.
The correct lewis structure for MgCl2 is shown in the image attached to this answer.
Answer: B is the answer took the test
Explanation: both electrons of Mg should be transferred to one O atom...
WILL GIVE A BRAINLIEST FOR THE ANSWER.
Pls open the picture for the question. I need the answer ASAP.
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Answer:
(i) There is a very fast rate at t1, as its slope is the most significant, at t2 the rate is still positive, but it has decreased compared to t1, and at t3 the rate is almost constant, as seen by the nearly flat slope.
(ii) The trend in the reaction rate is logarithmic, with a very fast reaction rate at the beginning that slowly decreases.
Explanation:
Two graduated cylinders, one filled with water to 20 millimeters and one containing a rock and water filled to 32 millimeters.
Use the image to determine the volume of the rock.
Initial volume:
mL
Final volume:
mL
Volume of rock:
cm3
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Answer:
1. 20
2. 32
3. 12
Explanation:
A balloon is floating around outside your window. The temperature outside is 31 ∘C , and the air pressure is 0.700 atm . Your neighbor, who released the balloon, tells you that he filled it with 4.10 moles of gas. What is the volume of gas inside this balloon? Express to THREE signficant figures.
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Answer:
the volume of gas inside this balloon = 146.3 L
Explanation:
Given that:
The temperature T = 31 °C = ( 31 + 273.15 )K = 304.15 K
The air pressure P = 0.700 atm
number of moles of gas n = 4.10 moles
Gas constant = 0.0821 L atm/K/mol
The objective is to calculate the volume of the gas inside the ballon.
Using the Ideal gas equation
PV = nRT
V = nRT/P
V = (4.10×0.0821×304.15)/0.700
V = 102.3799/0.700
V = 146.257 L
V = 146.3 L
Thus, the volume of gas inside this balloon = 146.3 L
I’m having trouble with this assignment please help.
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Q = m.c.AT
m = 50,0 g of iron
c = 0.450 J.g-1°C-1
AT = 10°C
Thus
Q = 50 * 0.450 * 10
Q = 225 J
Is the heat energy
Hope it helps xx
Explain the different between a molecule and a compound.
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Answer:
-A molecule is the smallesr part is compound whereas a compound is the combination of two or more atoms in a fixed proportion by wiehgt.
- A glass of water is an example of compound but a small portion of water can be called molecule.
Are starch molecules or glucose molecules bigger?
Answers
Answer: Starch
Explanation:
Why is starch larger than glucose? Based on the experiment, starch molecules are bigger in comparison to glucose molecules because they could not leave the tubing. This is supported by the presence of color change in the tubing for the starch test.
Starch molecules are polysaccharides and big sugar molecules, whereas glucose is a monomeric carbohydrate. Thus, starch molecules are bigger than glucose molecules.
What are starch molecules?Starch is an insoluble carbohydrate that is tasteless and soft sugar with molecular formula, (C₆H₁₀O₅)ₙ. They are categorized as polysaccharides as they are made of more than two sugars linked through glycosidic bonds.
The starch is a complex sugar molecule made of many glucose monomeric units linked by α 1,4 linkages. It is present in food sources and is consumed for energy. On the other hand, glucose is a simple carbohydrate that is categorized as a monosaccharide due to single sugar.
As starch is a polysaccharide and has n number of carbons they have a large molecular weight and structures as compared to the glucose molecule with less molecular weight.
Therefore, starch is a bigger molecule.
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plz answer fast i beg u
Which are not particles that enable electrical conductivity?
Select one:
a. delocalised electrons
b. molecules
c. mobile ions
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Answer:
The correct option is;
a. Delocalised electrons
Explanation:
The particles that enable electrical conductivity are the delocalised electrons
The metallic structure consists of identically shaped elements having positive ions that have a resultant alignment, surrounded by a vast array of deloclised electrons, which move freely in the metallic structure such that a metallic part usually has a high electrical conductivity.
Therefore, the freely moving delocalised electron in a metal give them the property of good conductors of electricity.
Which statement correctly describes the relationship between thermal energy and particle movement?
1 As thermal energy increases, particle movement does not change.
2 As thermal energy increases, it is not possible to predict particle movement.
3 As thermal energy increases, there is less particle movement.
4 As thermal energy increases, there is more particle movement.
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The correct statement that describes the relationship between thermal energy and particle movement is "As thermal energy increases, there is more particle movement".
WHAT IS THERMAL ENERGY?
Thermal energy is the energy that emanates from heat or change in temperature. Thermal energy is directly proportional to the movement of particles. This means that an increase in thermal energy depicts an increase in the kinetic energy (energy due to motion) of the particles involved.Hence, as thermal energy of substance increases, there is more particle movement of that substance.
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what's the atomic weight of salt ?
Answers
Answer:
58.44 g/mol
Explanation:
58.44 g/mol
Complete and write net ionic equation:
NH3 + HCI->
Answers
Answer:
IONIC EQUATION OF NH3 AND HCL IS NH4CL
Name any two mixture that can be separated by this distillation
Answers
Answer:
Simple distillation is used to separate salt from seawater, to separate sugar from water.
Explanation:
All the simple machines make work easier to do by changing the _____ or _____ of a force. A. size; type B. work; type C. size; direction D. type; direction
Answers
Answer:
C. size; direction
Explanation:
By definition, a machine is referred to any device that makes work easier. It takes force to do work, hence, work refers to the application of force over a particular distance. A machine aims at making the work easy by changing how it is done. Simple machines, which include: levers, pulleys, inclined planes etc. all carry out the same thing, which is to make work easier, by changing the size/magnitude and direction of the applied force.
A simple machine tends to change the size of the inputted force by increasing it over a shorter distance. The machine increases the force applied better than it can be done manually e.g. a plier and nutcracker increases/changes the applied force better than it can be done with bare hands.
Also, a simple machine can achieve making work easier by changing the direction at which the force is applied. The machine applies the force on the object in an opposite direction or contrary to the way it was manually applied.
What is the second quantum number for one of the electrons in the 4p energy
sublevel of bromine?
O A. 1 = 1
B. /= 3
C. /= 2
D. /= 4
Answers
Answer:
D. l=1
Explanation:
The second quantum number for one of the electrons in the 4p energy
sublevel of bromine is 1=1. Therefore, the correct statement is option A.
What is the second quantum number?The second quantum number also called the azimuthal quantum number describes the shape of the orbital.
The possible values of l for a given value of the principal quantum number (n) range from 0 to (n-1) where n is a principal quantum number that describes the size of the orbital and the energy of the electron, where possible values of l determine the shape of the orbital.
In the 4p energy sublevel of bromine, n is equal to 4 because the energy sublevel and fourth principal energy level are associated. For p orbitals, the possible values of l are 1, which corresponds to a bell-shaped orbital.
Therefore, the second quantum number for one of the electrons in the 4p energy sublevel of bromine is 1.
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how many oxygen atoms are in 7.25g of calcium nitrate
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Answer:
The answer to this question is approximately equal to 1.6 ×
[tex] 1.6 \times {10}^{23} atom \: o[/tex]
Which of the following is the BEST choice to contain small amounts of chemicals while they react?
electronic balance
test tube
coffee mug
graduated cylinder
Answers
Answer:
test tube
Explanation:
test tube is a very small thin glass in the science lab and it's contain small amount of chemicals as they react