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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Related Questions
Name five metal which are both dilute and memorable? class 10
Answers
BJECTIVE TYPE QUESTIONS
Fill in the blank spaces by choosing the correct words from the words given in list.
List : composition, heat, chemical, photosynthesis, physical
1. Heating of zinc oxide is a
change.
2. Burning of coal is a
change.
3. There is a change in state and
during a chemical change.
4. Plants make their food by the process of
5.
energy is generally given out or absorbed during a chemical change
Answers
Answer:
1.Physical change
2. Chemical change
3. Heat
4.photosynthesis
5. composition
A process which is unfavorable with respect to enthalpy, but favorable with respect to entropy Group of answer choices could occur at high temperatures, but not at lower temperatures. could not occur regardless of temperature. could occur at any temperature. could occur at low temperatures, but not at higher temperatures. none of the above
Answers
Answer:
could occur at any temperature.
Explanation:
The spontaneity of a reaction is what determines whether the reaction will occur or not. A spontaneous reaction occurs easily.
The spontaneity of a reaction is predicted by the sign of ∆G.
When ∆G is positive, the reaction is not spontaneous. When ∆G is negative, the reaction is spontaneous.
Note that;
∆G= ∆H - T∆S
Where;
∆H = Change in enthalpy
∆S = Change in entropy
T= temperature
If ∆H is unfavourable and ∆S is favourable, the reaction can proceed at all temperatures because ∆G will always be negative.
It should be noted that a process that is unfavorable as regards to enthalpy, but favorable with respect to entropy could occur at any temperature.
Enthalpy(∆H) serves as amount of internal energy that a compound has, entropy( ∆S) on the other hand serves as intrinsic disorder within the system.
However, spontaneity of a reaction determines likely hood of occurrence of a reaction, when the process is spontaneous, it makes the reaction to occurs easily.
We can conclude that whenever enthalpy is unfavourable and entropy of a system is favourable, then the spontaneity will be negative and the reaction will occur at any temperature.
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Which condition will probably not increase
the rate of reaction?
a. Adding water to dilute the reaction
mixture
b. Increasing the temperature
c. Adding a catalyst
d. Removing an oxide coating on a
metal
Answers
Answer:
i think A.
Explanation:
bc B. makes the molecules hight temp = move faster = more collisions = higher rate, C. it's use is to make reactions rates increase, D. somthung abt more surface area and easier collisions
use the the dot strict on the right to and the periodic table to determine the element represented.
sodium (Na)
potassium (K)
neon (Ne)
argon (Ar)
Answers
Answer:
Pottasium
Explanation:
because it is the nineteenth element
Answer:
The answer is B. Potassium.
Explanation: Potassium has 19 electrons that are organized like the image if you count the electrons on each obital. This answer is correct on edge 2020. Hope this helps!
What was the main aim of Cavendish’s work?
Answers
Answer:
The Cavendish experiment, performed in 1797–1798 by English scientist Henry Cavendish, was the first experiment to measure the force of gravity between masses in the laboratory and the first to yield accurate values for the gravitational constant
Explanation:
I think that's correct
Brainliest if answered correctly
How many Calcium (CA) atoms are in carbon tetrachloride
Answers
Answer:
What atoms are present in carbon tetrachloride?
There is 1 carbon, and 4 chlorine atoms (or chloride ions if you want to get technical). Tetra means 4 in Greek.
hope that helps❤
Answer:
there are no calcium atoms of n carbon tetrachloride
Which of the following statements about periodic trends is true?
O both electronegativity and atomic radius decrease from bottom to top and from left to right on
the periodic table.
O both electronegativity and ionization energy increase from bottom to top and from left to right
on the periodic table.
O both atomic radius and ionization energy increase from bottom to top and from right to left on
the periodic table.
O electronegativity, ionization energy and atomic radius all decrease from bottom to top and from
left to right on the periodic table.
Answers
both electronegativity and ionization energy increase from bottom to top and from left to right
on the periodic table.
How do the substances compare?
Answers
A chemical substance is composed of one type of atom or molecule.
A mixture is composed of different types of atoms or molecules that are not chemically bonded.
A heterogeneous mixture is a mixture of two or more chemical substances where the various components can be visually distinguished.
A homogeneous mixture is a type of mixture in which the composition is uniform and every part of the solution has the same properties.
Various separation techniques exist in order to separate matter, including include distillation, filtration, evaporation and chromatography. Matter can be in the same phase or in two different phases for this separation to take place. Matter can be broken down into two categories: pure substances and mixtures. Pure substances are further broken down into elements and compounds. Mixtures are physically combined structures that can be separated into their original components.
A chemical substance is composed of one type of atom or molecule.
A mixture is composed of different types of atoms or molecules that are not chemically bonded.
A heterogeneous mixture is a mixture of two or more chemical substances where the various components can be visually distinguished.
A homogeneous mixture is a type of mixture in which the composition is uniform and every part of the solution has the same properties.
Various separation techniques exist in order to separate matter, including include distillation, filtration, evaporation and chromatography. Matter can be in the same phase or in two different phases for this separation to take place.
in which instrument of the following the washer works works as a valve? a)syringe b)hydraulic garage lift c)air pump d)watre pump
Answers
Answer:
A
Explanation:
The instrument in which the washer works as a valve is A ; syringe
Each instrument listed have a washer and a valve, but of all the instruments listed above the instrument that its washer works also as a valve is the syringe.
A syringe is composed of a thin tube and a thinner hollow needle attached to the end of the thin tube. the needle is used and take in liquids and also expel liquids from the syringe ( i.e. washer and valve )
hence the instrument that its washer also functions as a valve is the syringe.
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A liquid that occupies a volume of 8.2L has a mass of 5.6kg. What is the density of the liquid in kg/L
Answers
Answer:
0.68
Explanation:
This is because the formula for finding density is mass/volume. Therefore the equation becomes 5.6/8.2 giving you 0.68
Consider the reaction. 2HF(g)—H2(g)+F2(g). What is the value of Keq for the reaction expressed in scientific notation
Answers
Answer:
A). 2.1 × [tex]10^{-2}[/tex]
Explanation:
Given reaction,
2[tex]HF[/tex] (g) ⇄ [tex]H_{2}[/tex] (g) + [tex]F_{2}[/tex] (g)
The concentrations are as following;
[tex]HF[/tex] = 5.82 × [tex]10^{-2}[/tex] M
[tex]H_{2}[/tex] = 8.4 × [tex]10^{-3}[/tex] M
[tex]F_{2}[/tex] = 8.4 × [tex]10^{-3}[/tex] M
So,
[tex]K_{eq}[/tex] = [([tex]H_{2}[/tex] ) × ([tex]F_{2}[/tex])] ÷ [[tex]HF[/tex]]^2
Now,
We can determine the value of [tex]K_{eq}[/tex] by substituting the values in above formula:
[tex]K_{eq}[/tex] = [ (8.4 × [tex]10^{-3}[/tex] M) × (8.4 × [tex]10^{-3}[/tex] M)] ÷ [(5.82 × [tex]10^{-2}[/tex])^2
= 2.08 * [tex]10^{-2}[/tex]
= 2.1 × [tex]10^{-2}[/tex]
∵ [tex]K_{eq}[/tex] = 2.1 × [tex]10^{-2}[/tex]
Thus, option A is the correct answer.
how many Molecules and atoms of the product 2H2O+ O2
Answers
Answer:
A water molecule is composed of two hydrogen atom and one oxygen atom but you can't simply take two hydrogen atom stick them onto an oxygen atom
Which of the following processes does NOT facilitate containment?
Answers
Answer:
b is the answr
Explanation:
The correct answer is Option (B) Enrichment of Uranium-235 is done.
What is Containment? Containment is the process of preventing pollution or contamination of the immediate site environment by dust, chemicals, and other materials to prevent corrosion.What is Corrosion?Corrosion is a natural process that converts a refined metal into a more chemically stable oxide.The degree of containment is directly proportional to the degree of toxicity present in the corrosion preventive substance being applied.Why other options are incorrect?Option (A) , (C) , (D) are the options that facilitate containment because these are the processes for preventing contamination.
Hence Option (B) is correct because enrichment of uranium-235 is achieved by the process of conversion So , It does not facilitate containment
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calculate the mass of magnesium needed to make 25g of magnesium oxide
mark brainliest of correct xx
Answers
Answer:
15g
Explanation:
First, you need to correct the answer to the previous question. The percentage by mass of Mg in MgO =
Mg = 24.3 amu
O = 16.0 amu
The total mass of MgO = 40.3 amu
To calculate the percent composition of Mg:
% = 24.3/40.3 x 100
% = 60
To calculate the mass of Mg needed to make 25g of MgO:
x/25g = 60%/100%
100x = (25)(60)
100x = 1500
x = 15g
2. Nitric oxide contains 46.66% nitrogen and 53.34% oxygen. Water contains 11.21% hydrogen and 88.79% oxygen. Ammonia contains 17.78% hydroger and 82.22% nitrogen. Use these data to verify the law of reciprocal proportions.
Answers
Answer:
The law of reciprocal proportions states that if two elements react individually with a given weight of a third element, the ratio of the masses with which they combine with the third element are either the same or a simple multiple of the ratio of the masses with which they combine with each other
The compounds formed includes;
1) Nitric oxide, NO
Nitrogen = 46.66% × 30.01 = 14
Oxygen = 53.34% × 30.01 = 16
2) Water, H₂O
Hydrogen = 11.21% × 18.01528 = 2
Oxygen = 88.79% × 18.01528 ≈ 16
3) Ammonia, NH₃
Hydrogen = 17.78% × 17.031 ≈ 3
Nitrogen = 82.22% × 17.031 ≈ 14
The ratio of nitrogen to oxygen in nitric oxide = 14:16 = 7:8
The ratio of nitrogen to hydrogen in ammonia = 14:3
The ratio in which hydrogen and oxygen combine with nitrogen = 3/16
The ratio of hydrogen and oxygen combine with each other in water = 2/16
Therefore, the ratio with which hydrogen and oxygen combine with nitrogen, is (2/3) times the ratio with which they combine with each other, which verifies the law of reciprocal proportions
Explanation:
When a vacancy exists in an inner electron shell of an atom (as a result of photoelectric effect, Compton scattering, or bombardment by other electrons), the energy liberated when this vacancy is filled, instead of emerging from the atom as fluorescent radiation, can be transferred to another electron of the atom, thereby ejecting the electron. Such an emitted electron is called a(n) _____ electron
Answers
Answer:
The answer is "Auger".
Explanation:
The Auger effect is an effect size when the vacancy of even an atom throughout the inner shell was complemented by the release of even an electron from the same atom. Whenever a central electron is lost, a higher energy level electron can drop into the void and release energy, which can be the result.
It's said that not all electrons in an atom have the same amount of energy. Is it the same for protons? Because if it's not then how come they have the same atomic number at the end?
Answers
Answer:
When an atom has an equal number of electrons and protons, it has an equal number of negative electric charges (the electrons) and positive electric charges (the protons). The total electric charge of the atom is therefore zero and the atom is said to be neutral.
I HOPE THIS HELPS !!!!!!!!!!!
Mole concept
Calculate the number of iodine atoms in 4.50g of iodine gas
Answers
Answer:
0.017g/mol
Explanation:
according to the mole concept to calculate the number of moles of a substance you use the formula
number of moles= mass/molecular mass
=4.5g/254g/mole
=0.017moles
I hope this helps and sorry if it's wrong
What tricks to use to differentiate between Ionic and Covalent bonds
Answers
Answer: first of all an ionic bonds is the electrostatic force of attraction between opposite ions and and covalent bonds is the bond between different elements mostly non metals or the sharing of electrons between elements which are mostly non metals.
Explanation: metals and non metals react to form ionic compounds
and non metals react to form covalent bonds
HOW TO DIFFERENTIATE
ionic solids the particles are charged and the forces between them are strong
covalent solids the particles are not charged and the forces between them are weak
now i would differentiate using their properties
ionic bonds / compounds
have high melting point
have low melting point
They are soluble in water
and they conduct electricity even when melted or dissolved in water
covalent bonds /compounds
they have low melting point
they have low melting point
They are insoluble
they do not conduct electricity
HOPE THIS HELPS!!!
can u plz solve it n send the answer
Answers
1. Cl2 + H2O → HOCl + HCl
2. Tooth decay starts when when the pH of the mouth is lower than 5.5. Tooth enamel is made up of calcium phosphate and it is one of the hardest substances of the body. But it is corroded when the pH is less than 5.5. The bacteria of our mouth produce acids by degradation of sugar and food particles remaining in our mouth after eating food.
3. Fluorine salts are added in toothpaste to protect our teeth from tooth decay. Fluorine salts are mildly basic, so they neutrelise the acid in our mouth that leads to tooth decay.
4. Tincture of iodine is iodine, pottasium iodide and sodium iodide dissolved in ethanol. Iodine acts in an antiseptic manner by destroying microbial proteins and DNA.
5. Tincture of iodine is clear and reddish brown liquid.
Analysis of an ore of calcium shows that it contains 13.61 g calcium and 21.77 g oxygen in a 46.28-g sample. Calculate the percent composition of this compound.
Answers
Answer:
29.41% of Calcium and 47.04% of Oxygen
Explanation:
The percent composition of an atom in a molecule is defined as 100 times the ratio between the mass of the atom and the mass of the molecule.
The mass of the molecule of the problem (Ore) is 46.28g. That means the percent composition of Calcium is:
13.61g / 46.28g * 100 = 29.41% of Calcium
And percent composition of Oxygen is:
21.77g / 46.28g * 100 = 47.04% of Oxygen
Match each lab incident to the item of PPE that will protect you from it. Each item of PPE will only be used once.
While picking up a buret, an unknown solution left by a previous solution drips onto your hand._______________
While pulling an empty beaker off the shelf at the beginning of lab, it slips out of your hand onto the floor _______
While checking on a stirring solution, the solution splashes up towards your face. _______
While transferring a solution from a flask to a beaker, the solution accidentally spills down the front of the lab bench, __________
A. Gloves
B. Lab coat
C. Goggles
D. Closed-toe shoes
Answers
While picking up a buret, an unknown solution left by a previous solution drips onto your hand - Gloves
While pulling an empty beaker off the shelf at the beginning of lab, it slips out of your hand onto the floor - Closed-toe shoes
While checking on a stirring solution, the solution splashes up towards your face - Goggles
While transferring a solution from a flask to a beaker, the solution accidentally spills down the front of the lab bench - Lab coat
Explanation:
The full form of PPE is 'Personal Protective Equipment'.The PPE items we use in labs are : Lab coat: Protection of clothing and skin from accidental spilling of hot liquid or toxic substances. Gloves: Protection from hands from chemicals, hot objects, sharp tools, or electricityGoggles: Protection of the eye from any chemicals, toxic vapor, chemical debrisFace shield: Protection of the face from any chemicals, toxic vapor, chemical debrisClosed-toe shoes: Protection from feet from chemicals, hot objects, sharp tools, or electricitySo, according to the question. the matches will be:
While picking up a buret, an unknown solution left by a previous solution drips onto your hand - Gloves
While pulling an empty beaker off the shelf at the beginning of lab, it slips out of your hand onto the floor - Closed-toe shoes
While checking on a stirring solution, the solution splashes up towards your face - Goggles
While transferring a solution from a flask to a beaker, the solution accidentally spills down the front of the lab bench - Lab coat
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Given: CNO2
a) Draw the Lewis structures (Do not forget to show the calculation of the number of available valance electrons)
b) Name the geometry shape
c) Indicate the polarity (polar or non-polar)
Answers
Answer:
since there are no lone pairs on the central atom, this would be a trigonal planar molecule. It's polar because the shape of it does not cancel its polarity (you can think of it as not having a balanced electronegativity pull, since the nitrogen is pulling on one side, and the oxygens are pulling on the other. It would be nonpolar if the there were 3 Oxygens).
Sorry this take a little bit long. I was a little confused by the odd valence number
For the reaction 2A + 4B ----> 2C + 2D, at a particular instant in time, the rate of the reaction is 0.0352 M/s. What is the rate of change of B? Show Work!
A. 0.0088 M/s
B. -0.0088 M/s
C. -0.141 M/s
D. -0.0352 M/s
E. 0.141 M/s
Answers
Explanation:
The given chemical equation is:
[tex]2A + 4B -> 2C + 2D[/tex]
The rate of the reaction is 0.0352 M/s.
During the course of the reaction, the rate of reactants decreases, and the rate of products increases.
The rate of disappearance of B is shown below:
[tex]rate=-\frac{1}{4} \frac{d[B]}{dt}[/tex]
So, rate of change of B is :
[tex]rate of change of B =- rate * 4\\=-0.0352 M/s * 4\\=-0.1408M/s\\\\=-0.141M/s[/tex]
Option C.
In the given reaction, rate of change of reactant B is equal to -0.141 M/s.
What is the rate of reaction?Rate of any chemical reaction defines the speed of the completion of that reaction.
In the question given reaction is:
2A + 4B ----> 2C + 2D
Rate of reaction = 0.0352 M/s.
Rate of the reaction with respect to the reactant B is written as:
Rate = [tex]${\rm{ - }}\frac{{\rm{1}}}{{\rm{4}}}\frac{{\left[ {{\rm{dB}}} \right]}}{{{\rm{dT}}}}$[/tex], where negative sign shows the disappearance of reactant B.
Rate of change of B i.e. [tex]$\frac{{{\rm{dB}}}}{{{\rm{dT}}}}$[/tex] = 4 × (-rate)
[tex]$\frac{{{\rm{dB}}}}{{{\rm{dT}}}}$[/tex] = 4 × (-0.0352) = -0.1408 = -0.141 M/s
Hence, -0.141 M/s is the rate of change of B.
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how do i calculate the concentration of a certain solution
Answers
Answer:
Divide the mass of the solute by the total volume of the solution. Write out the equation C = m/V, where m is the mass of the solute and V is the total volume of the solution. Plug in the values you found for the mass and volume, and divide them to find the concentration of your solution.
What's the velocity of a ball falling with 100 joules of kinetic energy and a mass of 2 kilograms?
А. 3 m/s
B. 5 m/s
C. 7 m/s
D. 8 m/s
E. 10 m/s
Answers
Answer:
E
Explanation:
kinetic energy of linear motion
[tex]k.e = \frac{1}{2} m {v}^{2} [/tex]
kinetic energy, K.e= 100joules
mass, m = 2kg
velocity, v =?
substituting the values into the formula :
[tex]100joules = \frac{1}{2} \times 2kg \times {v}^{2} [/tex]
[tex] {v }^{2} = 100[/tex]
[tex]v = \sqrt{100 } [/tex]
[tex]v = 10m { \sec }^{ - 1} [/tex]
Using dobereiner's triads, what conclusion could have been made about magnesium
Answers
Answer:
Triads were groups of 3 elements with similar chemical and physical properties. Beryllium, magnesium, and calcium are all earth alkalis found in the earth
Explanation:
Which is the formula mass of (NH4)2SO4?
96.07 amu
114.12 amu
116.17 amu
132.17 amu
Answers
Answer:
132.17amu
Explanation:
(14.01+1.01 multiplied by 4)=18.05×2=36.1
36.1+32.07= 68.17
16.00×4=64
68.17+64=132.17
Answer:
132.17 amu
Explanation:
just took the test. got 100
Please hurry this is due tomorrow morning
A student is studying the ways different elements are similar to one another. Diagrams of
atoms from four different elements are shown below.
Which two atoms are of elements in the same group in the periodic table?
F Atom 1 and Atom 2
G Atom 1 and Atom 4
H Atom 2 and Atom 3
J Atom 3 and Atom 4
