Key concepts
Physics
Chemistry
Density
Liquids
Introduction
You probably know that when solid objects are placed in liquid, they can sink or float. But did you know that liquids can also sink or float? In fact, it is possible to stack different layers of liquids on top of one another. The key is that all the different layers must have different densities. You can stack them by picking several liquids with a range of densities or by varying the density of one liquid by adding chemicals such as sugar or salt to it. If you choose colored liquids or add food coloring to each layer, you can even create a whole rainbow of colors in one single glass! Want to see for yourself? In this science activity you will stack several liquids—one by one—and create a colorful density column!
Background
Whether an object sinks or floats depends on its density compared with the density of the liquid into which it is dropped. All types of matter—solids as well as liquids—are made up of many different atoms. Depending on the mass of these atoms, their size and the way they are arranged, different substances will have different densities. The density is characteristic for each individual compound and defined as the mass of a compound divided by its volume. In other words, the more matter there is in a certain amount of volume, the denser a substance is. One cubic centimeter of rock, for example, is much heavier than a cubic centimeter of wood. This is because there is much more matter in the same volume of rock compared with the wood.
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Liquids can also have different densities. Freshwater, for example, has a density of about one gram per cubic centimeter at room temperature. Any compound—liquid or solid—that has a higher density than water will sink whereas substances with a lower density than that will float. You can test that for yourself by gathering several liquids that you have in your kitchen such as vegetable oil, corn syrup, dishwashing soap, water, rubbing alcohol and more. Which one of these do you think will sink or float in water? Find out in this activity!
Materials
Glass or cup
Water
Food coloring
Scissors
Rubber band (wide)
Small piece of wax
Popsicle stick
At least two small, clear jars or transparent mini cups (two ounces) with lids
Permanent marker
Masking tape
Three tablespoons
Dark corn syrup
Vegetable oil
Penny
Paper towels
Rubbing alcohol, dishwashing soap and other liquids (optional)
Sugar (optional)
Preparation
Gather all your materials at a workspace that can tolerate spills of all the liquids.
Fill a cup with tap water and add a couple of drops of food coloring to the water.
Ask an adult to help you cut and prepare small pieces (about 0.5 by 0.5 centimeter) of the rubber band, the popsicle stick and the wax.
Place the two empty jars in front of you (without the lids) and label them “1” and “2” with a piece of tape and the permanent marker.
Procedure
Take a clean tablespoon and pour two tablespoons of corn syrup in jar 1.
With the second tablespoon, carefully pour two tablespoons of colored water into jar 1 on top of the corn syrup. What happens to the water on top of the corn syrup? Does it mix or stay separate?
Use the third clean tablespoon to pour two tablespoons of vegetable oil in jar “1” on top of the colored water. Do you see mixing of the liquids? What happens to the oil? Does it float on top or sink to the bottom?
Now take empty jar 2 and add the same liquids—but in reverse order. Start by pouring in two tablespoons of vegetable oil.
Which of the following compounds below would possess it trigonal planar molecule or geometry?
PHOTO ABOVE
HELP ME IN MY TEST
Answer:
B - BF3
Explanation:
BF3 has 3 bonds around the central atom and now lone pairs on it. This matches the geometry of a trigonal planar molecule as per the VSEPR Model.
Molecules have two distinct characteristics: form and geometry. Geometry includes the lone pair encircling the focal element whereas shape excludes it. Therefore, the correct option is option B.
What is VSEPR theory?Valence shell electron repulsive force is what VSEPR stands for. Based on the valence electron pairs that are prevalent around the core element of the molecule, the VSEPR theory is employed to predict the structure and geometry of molecules.
According to VSEPR theory, Lone pair lone pair repulsion is greater than bond pair bond pair repulsion. The core atom of BF[tex]_3[/tex] is surrounded by three bonds and contains no lone pairs. According to the VSEPR Model, this corresponds to the geometry of such a trigonal planar molecule.
Therefore, the correct option is option B.
To know more about VSEPR theory, here:
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What volume will 250. mL of gas at STP occupy ig the pressure changes to 2.0 atmospheres and the temperature changes at 30 degrees Celsius
Answer:
it is 75 degrees
Explanation:
Volume is 138.7 mL.
The equation for calculation of volume is as follows:-
[tex]\frac{P_1V_1}{T_1} =\frac{P_2V_2}{T_2}[/tex]
STP:-
Temperature=273 K
Pressure=1 atm
[tex]\frac{1 atm\times250mL}{273 K} =\frac{2 atm\times V_2}{303\ K}\\V_2=138.7\ mL[/tex]
Hence, the volume is 138.7 mL.
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Answer:
3. The total number of protons and neutrons in an atom is its mass number.
4. The mass number of a helium atom with 2 protons and 2 neutrons is 4.
5. A beryllium atom with 4 protons and a mass number of 9 has 5 neutrons.
6. The chemical symbol is Ne. The atomic number is 10. The mass number is 22.
7. Neon-22
8. Not enough information
How do we balance Zn + HNO3 Zn(NO3)2 + NO + H20
3Zn + 8HNO₃⇒ 3Zn(NO₃)₂ + 2NO + 4H₂O
Further explanationEqualization of chemical reaction equations can be done using variables. Steps in equalizing the reaction equation:
1. gives a coefficient on substances involved in the equation of reaction such as a, b, or c etc. 2. make an equation based on the similarity of the number of atoms where the number of atoms = coefficient × index between reactant and product 3. Select the coefficient of the substance with the most complex chemical formula equal to 1For gas combustion reaction which is a reaction of hydrocarbons with oxygen produces CO₂ and H₂O (water vapor). can use steps:
Balancing C atoms, H and the last O atoms
Reaction
Zn + HNO₃⇒ Zn(NO₃)₂ + NO + H₂O
1. gives a coefficientaZn + bHNO₃⇒ Zn(NO₃)₂ + cNO + dH₂O
2. make an equationZn : left = a, right =1 ⇒a=1
H : left = b, right = 2d⇒ b=2d (eq 1)
N : left = b, right = 2+c⇒b=2+c (eq 2)
O : left = 3b, right = 6+c+d ⇒3b=6+c+d(eq 3)
From eq 1 and eq 33(2d)=6+c+d
6d=6+c+d
5d=6+c (eq 4)
From eq 2 and eq 33(2+c)=6+c+d
6+3c=6+c+d
2c=d (eq 5)
From eq 4 and eq 55(2c)=6+c
10c=6+c
9c=6
c = 2/3
input eq 5
d = 2 x 2/3
d = 4/3
input eq 1
b = 2 x 4/3
b = 8/3
The equation
aZn + bHNO₃⇒ Zn(NO₃)₂ + cNO + dH₂O to
Zn + 8/3HNO₃⇒ Zn(NO₃)₂ + 2/3NO + 4/3H₂O x 3
3Zn + 8HNO₃⇒ 3Zn(NO₃)₂ + 2NO + 4H₂O
Match the element with their place on the periodic table.
Question 4 options:
Period 4, group 5-
Period 5, group 7-
Period 7, group 5-
Period 5, group 4-
1. dubrium
2. technetium
3. zirconium
4. vanadium
Answer:
Period 4, group 5- Vanadium
Period 5, group 7- Technetium
Period 7, group 5- Dubnium
Period 5, group 4- Zirconium
Explanation:
Learning Task No. 2: Using the Periodic Table of Elements, determine the ele-
ments asked in each guide question. Write your answer in your notebook.
Guide Questions:
1. Which elements are likely to lose electrons?
2. Which elements are likely to ain electrons?
3. Which type of elements are likely to have no electrical charge at all?
Explanation:
1 metal they are likely to lose an electron
2non metals
3 Nobel gases because they are not reactive with stable valance number
Which phrase describes density?
O height of a point above sea level
O force pushing on an area or a surface
O amount of mass in a certain volume
O amount of matter an object contains
Answer:
C: amount of mass in a certain volume
Explanation:
Just took the quiz and got 100%
Un compuesto formado por carbono, hidrógeno y oxígeno tiene una masa de 4,6 g. Se hace reaccionar con 9,6 g de oxígeno dando 8,8 g de CO2 y 5,4 g de agua. Si cogemos 9,2 g de un compuesto en un volumen 5,80l en P= 780 mmHg a una temperatura de 90ºC. Calcula la fórmula empírica y molecular.
Answer:
La fórmula empírica y molecular es: C₂H₆O.
Explanation:
Para calcular la formula empírica y molecular del compuesto debemos primero plantear la reacción:
[tex] C_{x}H_{y}O_{z} + O_{2} \rightarrow CO_{2} + H_{2}O [/tex]
Necesitamos encontrar "x", "y" y "z". Para ello, tenemos que recordar que la masa de carbono e hidrógeno producida está relacionada con la cantidad de C y H inicial (del compuesto):
Para el H:
CHO → H₂O
y 5,4g
[tex] \frac{2*1 g}{18 g} = \frac{y}{5,4 g} \rightarrow y = 0,6 g [/tex]
Para C:
CHO → CO₂
x 8,8g
[tex] \frac{12 g}{44 g} = \frac{x}{8,8 g} \rightarrow x = 2,4 g [/tex]
Para el O:
[tex] z = 4,6 g - 2,4 g - 0,6 g = 1,6 g [/tex]
Ahora mediante el calculo de los moles del C, H y O podemos encontrar la fórmula empírica:
Para el H:
[tex] n_{y} = \frac{m}{Pm} = \frac{0,6 g}{1 g/mol} = 0,6 moles [/tex]
Para el C:
[tex] n_{x} = \frac{m}{Pm} = \frac{2,4 g}{12 g/mol} = 0,2 moles [/tex]
Para el O:
[tex] n_{z} = \frac{m}{Pm} = \frac{1,6 g}{16 g/mol} = 0,1 moles [/tex]
[tex] C_{\frac{n_{x}}{n_{z}}}H_{\frac{n_{y}}{n_{z}}}O_{\frac{n_{z}}{n_{z}}} = C_{\frac{0,2}{0,1}}H_{\frac{0,6}{0,1}}O_{\frac{0,1}{0,1}} = C_{2}H_{6}O_{1} [/tex]
Entonces, la fórmula empírica del commpuesto formado es C₂H₆O.
Ahora para determinar la fórmula molecular podemos usar la siguiente relación:
[tex] \frac{Pm}{Pm_{e}} = n [/tex]
[tex] F_{m} = n*F_{e} [/tex]
[tex] F_{m} = \frac{Pm}{Pm_{e}}*F_{e} [/tex]
En donde Fm (fórmula molecular) y Fe (fórmula empírica) están relacionadas por n.
El valor de Pm lo obtenemos de la ecuación del gas ideal:
[tex]PV = nRT = \frac{m}{Pm}RT[/tex]
[tex] Pm = \frac{mRT}{PV} = \frac{9,2 g*0,082 L*atm/(K*mol)*(90 + 273 K)}{1.02 atm*5,80 L} = 46,3 g/mol [/tex]
[tex] F_{m} = \frac{46,3 g/mol}{(2*12 + 6*1 + 16)g/mol}*C_{2}H_{6}O_{1} = 1.00*C_{2}H_{6}O_{1} = C_{2}H_{6}O_{1} [/tex]
Por lo tanto, la fórmula molecular es la misma que la fórmula empírica, a saber C₂H₆O.
Espero que te sea de utilidad!
Radon-222 is an alpha emitter with a half life of 3.82 days.
1. What is the mass number of the daughter isotope?
2. What is the element symbol of the daughter isotope?
3. What is the atomic number of the daughter isotope?
The daughter isotope (a decay product): Polonium (Po)
Further explanationRadioactivity is the process of unstable isotopes to stable isotopes by decay, by emitting certain particles,
alpha α particles ₂He⁴ beta β ₋₁e⁰ particles gamma particles γ positron particles ₁e⁰
Radon-222 emits alpha α particles ₂He⁴ , so the atomic number decreases by 2, mass number decreases by 4
Reaction
[tex]\tt _{86}^{222}Rn\Rightarrow _{84}^{218}+_2^4He[/tex]
1. The mass number of the daughter isotope = 218
2 and 3. If we look at the periodic system, the element with atomic number 84 is Polonium (Po)
A metal object has a density of 2 g/ml. When placed in a graduated cylinder with 500 ml of water, the
water rises to 508 ml. What is the mass of the metal object?
Answer:
The answer is 16 gExplanation:
The mass of a substance when given the density and volume can be found by using the formula
mass = Density × volumeFrom the question
density = 2 g/ml
volume = final volume of water - initial volume of water
volume = 508 - 500 = 8 mL
We have
mass = 2 × 8
We have the final answer as
16 gHope this helps you
Which of the following is NOT an example of a chemical change? *
O Corrosion
O Grinding
O Combustion
O Rust
combined aggregation of minerals
Answer:
Rocks
Explanation:
The combined aggregation of minerals are called rocks. There are three types of rocks Igneous Rocks, sedimentary rock, and metamorphic rocks.
Rocks are formed due to the repetitive, orderly, geometrical internal arrangement of minerals. Minerals undergo several processes such as weathering, crystallization, erosion, and sedimentation to form rocks.
Hence, the combined aggregation of minerals is called rocks.
Suppose the moon orbited the earth just half as fast as it does now.
How many high tides would any one area have in one day?
A-3
B-2
C-1
D-4
Answer:
Explanation: The correct answer is 1. Do not put 2 .
Which scientist did people think was insane so they dismissed his ideas for almost 2000 years?
Hydrogen atoms are excited by a laser to the =4 state and then allowed to emit.
What is the maximum number of distinct emission spectral lines (lines of different wavelengths) that can be observed from this system? Calculate the wavelength of the 4⟶3 transition.
Answer:
1875 nm
Explanation:
Given the Rydberg formula for hydrogen: 1/λ = R(1/n₁² - 1/n₂²)
where R ≈ 1.097* 10^7 /m
Hence;
1/λ = 1.097* 107/m * (1/3² - 1/4²) = 5.3 * 10^5/m
λ = 1.875 * 10-6 m = 1875 nm
in atmosphere water is solute give reason
Answer:
water vapour is there
Explanation:
thats all i know
i dont get what it means by of touch
Answer:
So I don't know what do you mean by that, please be a little specific.
Explanation:
^^
Help pleaI’ll give brainliest
Which element has the
greatest number of valence electrons available for bonding?
O selenium
Oboron
O calcium
O chlorine
the ability for a substance to rust is
a. oxidation
b.rustability
c.magnetic attraction
d.reactivity
Answer:
i think it is letter b. rustability but not so sureeee
For an object that has a volume of 24.5 mL and a mass of 102g, calculate the density of the object
Answer:
The answer is 4.16 g/mLExplanation:
The density of a substance can be found by using the formula
[tex]density = \frac{mass}{volume} \\ [/tex]
From the question
mass = 102 g
volume = 24.5 mL
We have
[tex]density = \frac{102}{24.5} \\ = 4.163265306...[/tex]
We have the final answer as
4.16 g/mLHope this helps you
Which components are part of all scientific investigations? Check all that apply.
Answer:
Steps of a scientific investigation include 1. make observation
2. ask a question
3. form a hypothesis
4. test the hypothesis
5. analyze results
5 , drawing conclusions,
6. and communicating the results
Which tissues and organs belong to the Musculoskeletal System?
a boy walking in the street potential or kenetic energy?
Answer:
[tex]\boxed {\tt Kinetic \ energy}[/tex]
Explanation:
First, let's define kinetic energy and potential energy.
Kinetic
energy an object has due to motionPotential
energy an object has stored due to its position, charge, arrangement or other factorsSince the boy is walking down the street, the boy is in motion. Therefore, the energy must be kinetic energy.
If 23,000 joules of energy are used to heat mercury by 4.00 °C, what is the mass of the mercury?
What is the volume of 25.3 g of silver if the density of silver is 10.5 g/mL?
Answer:
MARK AS BRAINLIST
Explanation:
density = mass/volume
mass=25.3
density =10.5
10.5=25.3/v
v=25.3/10.5
=2.40
What is the atomic number of an atom?
O the number of neutrons
O the number of electrons and neutrons
O the number of protons
the number protons and neutrons
What information does a subscript in a chemical formula provide? Choose all that apply. * The charge of that atom while in the compound How many of each atom are present in the compound How many valence electrons each element has while in the compound How many valence electrons each element starts with In ionic, the simplified ratio of atoms in relation to each other
Answer:
B. How many of each atom are present in the compound
D. the simplified ratio of atoms in relation to each other
Explanation:
In a chemical formula, chemical elements or atoms are represented by a chemical symbol for example Fe for iron and Na for sodium, and the number of each atom is represented by a subscript such as CO2, where 2 is a subscript representing 2 atoms of oxygen.
A subscript represents the number of each atom in the compound and the simplified ratio of atoms in relation to each other. The simplified ratio of atoms in relation to each other means subscript shows the contribution of both the atoms in the compound, for example: N2 + 3H2 => 2NH3, it means the subscript showing the ratio or proportionate of atoms that is 2:2 for both nitrogen and hydrogen.
The subscript is always written below and to the right of the chemical symbol.
Hence, the correct answer is "B. How many of each atom are present in the compound and D. the simplified ratio of atoms in relation to each other"
How does an object's mechanical energy change as its speed (velocity) increases?
Answer:
The mechanical energy of the system increases, provided there is no loss of energy due to friction. The energy would transform to kinetic energy when the speed is increasing. The mechanical energy of the system remains constant provided there is no loss of energy due to friction.
Explanation:
Based on the Phase Change Graph below, what is the Melting Point for this point
substance?
Answer:
Where is the phase melting graph? Can't seem to find it
What’s this called
Please ASAP
Answer:
carbon dioxide CO[tex]{2}[/tex]
Explanation:
Double Polar Covalent bonds with CO2
Explanation:
Keep in mind that CO2 is a nonpolar molecule