Answer:
Dissolving a solid in liquid, such as table salt in water, is a physical change because only the state of the matter has changed. Physical changes can often be reversed. Allowing the water to evaporate will return the salt to a solid state.
Photoelectric effect will occur only if frequency of light striking an electron in a metal is above a certain threshold frequenci
The statement is correct. The photoelectric effect refers to the phenomenon where electrons are ejected from the surface of a material when it is exposed to light. The frequency of light striking an electron in a metal must be above the threshold frequency in order for the photoelectric effect to occur.
The statement is correct. The photoelectric effect refers to the phenomenon where electrons are ejected from the surface of a material when it is exposed to light. However, for the photoelectric effect to occur, the frequency of the incident light must be above a certain threshold frequency.
The threshold frequency is the minimum frequency of light required to dislodge electrons from the material. Below this threshold frequency, regardless of the intensity or duration of the light, no electrons will be emitted.
This behavior can be explained by the particle-like nature of light, where light is composed of discrete packets of energy called photons. The energy of a photon is directly proportional to its frequency. Only photons with energy greater than or equal to the binding energy of the electrons in the material can dislodge them.
Therefore, the frequency of light striking an electron in a metal must be above the threshold frequency in order for the photoelectric effect to occur.
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The graph shows five data points collected in an investigation of the relationship between the concentration of alcohol dissolved in water and its density. The relationship was expected to be linear. Which of the data points most likely resulted from an error in procedure? a 1 b 2 c 4 d 5
In comparison to modern, highly accurate density meters or pycnometers, hydrometers are far less accurate and temperature.
Thus, Although they require very large sample sizes, hydrometers are rather simple to operate. Usually, 300 to 500 ml per measurement are required. Hydrometers frequently require calibration off-site as well.
With measurements taken by eye, user error is a major issue, and temperature management is especially challenging. Inaccurately bringing and maintaining samples at temperature might take a long time, and once more, user perception of temperature levels is used to determine temperature levels.
Pycnometers and hydrometers have a further problem in that the findings of alcohol measurement are challenging to evaluate and record.
Thus, In comparison to modern, highly accurate density meters or pycnometers, hydrometers are far less accurate and temperature.
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What is the formula for iron(II) phosphide?
(Fe2P)
The formula for iron(II) phosphide is Fe₂P.
What is a Chemical formula?This is a term used in chemistry which is used to identify each constituent element by its chemical symbol and indicates the proportionate number of atoms of each element.
In this scenario, the chemical compound of iron and phosphorus, with a formula of Fe₂P and it has a physical appearance is grey, hexagonal needles which is formed from the reaction between the elements Iron and phosphorus at an elevated or high temperature and the product which is formed is a phosphorylated molecule thereby making it the most correct choice.
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Determine the heat (q) required to raise the temperature of 80.0 grams of metal from 28.0 °C to 53.0 °C. Assume the specific heat of the material is 0.8 J/g°C. Be sure to use proper labels, fill in all blanks, and use complete sentences where applicable for full credit.
Heat (q) = ______________ J
Mass (m) = ____________ g
heat (s) = ______ J/g°C
Initial temp (T1) = ______ °C
Final temp (T2) = _______ °C
Is the process endothermic or exothermic? _______________________________
Answer:
Explanation:
m= 80.0 g
Cp=0.8 J/gc
Change in T= 25
q=Cp X m X T =0.8 X 80.0 X 25 =1600J
Postive q or enthalpy makes it endothermic.
a gas mixture at 20.0 C and 2.0 atm contains 0.40 mol of H2, 0.15 mol of O2, and 0.50 mol of N2. Assuming ideal behavior, what is the partial pressure of hydrogen gar [H2] in the mixture?
The partial pressure of hydrogen gas in the mixture is:0.53334 atm.
What is partial pressure?
partial pressure. noun. the pressure that a gas would have if it took up the entire volume that the mixture of gases currently occupies.
P total,and the total number of moles in the mixture would be,
n total=nH2+nO2+nN2
This means that you could write
P total.V=ntotal.RT
p total=n total.RT/V
This is equivalent to
p total=[nH2+nO2+nN2].RT/V
therefore,
P total =PH2+PO2+pN2
now, to get the partial pressure of,let's Hydrogen gas
RT/V=Ptotal/nH2+nO2+nN2
therefore
PN2=XN2.p total
similarly,
PO2=XO2.p total
PN2=XN.p total
The total number of moles will be
\(ntotal\) = 0.40+0.15+0.50=1.50 moles.
\(PH2\)=0.40/1.50*2.0 atm =0.5334 atm.
\(PO2\)=0.15/1.50*2.0 atm =0.2 atm.
\(PN2\)=0.50/1.50*2.0 atm =0.66 atm.
Hence, the partial pressure of hydrogen gas in the mixture is:0.53334 atm.
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What volume of CO2(g), measured at STP is produced if 15.2 grams of CaCO(s) is heated?
Answer:
Volume = 3.4 L
Explanation:
In order to calculate the volume of CO₂ produced when 15.2 g of CaCO₃ is heated, we need to first write out the balanced equation of the thermal decomposition of CaCO₃:
CaCO₃ (s) + [Heat] ⇒ CaO (s) + CO₂ (g)
Now, let's calculate the number of moles in 15.2 g CaCO₃:
mole no. = \(\mathrm{\frac{mass}{molar \ mass}}\)
= \(\frac{15.2}{40.1 + 12 + (16 \times 3)}\)
= 0.1518 moles
From the balanced equation above, we can see that the stoichiometric molar ratios of CaCO₃ and CO₂ are equal. Therefore, the number of moles of CO₂ produced is also 0.1518 moles.
Hence, from the formula for the number of moles of a gas, we can calculate the volume of CO₂:
mole no. = \(\mathrm{\frac{Volume \ in \ L}{22.4}}\)
⇒ \(0.1518 = \mathrm{\frac{Volume}{22.4}}\)
⇒ Volume = 0.1518 × 22.4
= 3.4 L
Therefore, if 15.2 g of CaCO₃ is heated, 3.4 L of CO₂ is produced at STP.
QUESTION 5
How can you increase the kinetic energy of the particles in a substance?
Answer: A rise in temperature increases the kinetic energy and speed of particles; it does not weaken the forces between them. The particles in solids vibrate about fixed positions; even at very low temperatures. Individual particles in liquids and gases have no fixed positions and move chaotically.
Answer:
energy kinetic particles in substance
In a science demonstration, a teacher mixed zinc (Zn) with hydrogen chloride (HCl) in a flask and quickly attached a balloon over the mouth of the flask. Bubbles formed in the solution and the balloon inflated.
What most likely occurred during this demonstration?
a.The Zn and HCl both retained their identity.
b.Either Zn or HCl, but not both, retained its identity.
c.Evaporation of one of the substances occurred.
d.One or more new substances formed.
Answer:
a. The Zn and HCl both retained their identity.
Which level is made up of organisms that break down dead organisms?
Answer:
Explanation:
decomposers
Two cities in Germany are located 25 km apart. What is the
distance in miles?
Answer:
15.5343
Explanation:
In a physical change the make up of matter is changed.
O True
O False
Answer:
yes it is true
Explanation:
evaporation occurs when burning liquid water changes into gas.
what is it I need help
Which object will have the greatest gravitational pull?
Question 5 options:
Venus
Sun
Earth
Moon
Answer:
the sun i think because the sun has the greatest gravitational pull
Based on periodic trends and the data in the table above, which of the following is the most probable value for the ionic radius of K+?
Based on periodic trends, the most probable value for the ionic radius of K⁺ is 133 pm.
What are periodic trends?
Periodic trends are the observation which are seen in the chemical and physical elements found in the periodic table.
Periodic trends is based on the periodicity of elements.
Periodicity is the variation seen in the chemical and physical properties of the elements in the period table in a regular pattern, both down the groups and across the periods.
The periodic trends observed in metallic ions is that ionic radius of metallic ions increase down a group but decreases across a period.
Based on this periodic trend, the most likely size of the potassium ion, K⁺ is 133 pm.
In conclusion, the ionic radius of metallic ions increase down a group and decrease across a period.
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how would you prepared pure water from the mixture of impure water? explain with experiment.
Explanation:
Hello, there are alot method to separate the impurities from water. One of those & best method for purification of water is Distillation.
During distillation the given apparatus are set as shown in figure. After arrangement we put the impure water in distillation flask & there are two mouth of flask one is attached to condenser & other is covered. There are two tubes in the middle of the condenser in which water comes in from one and water goes out from the other and this happens continuously. The condenser is used to convert the collected water vapours into liquid water so that it can be collected easily in recieving flask.
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Density equals _____.
volume divided by mass
mass divided by volume
weight divided by area
weight divided by volume
PLEASE HELP it’s due in 30 minutes
Answer:
1-6
3 1 3 3 2 2
Explanation:
The first chemical equation was designed by
Answer:
Jean Beguin
Explanation:
The first chemical equation was diagrammed by Jean Beguin in 1615.
A solid block of substance is 78.0 cm by 55.0 cm by 35.0 cm and it weighs 569 g. What is its density in g/cm3?
The density of the solid block is 3.79 * 10⁻³ g/cm³.
What is the density of substance?The density of a substance is defined as the ratio of mass and volume of a substance.
Density = mass/volumeDensity measure how close together the particles of a given mass of a substance is. Substances with high density have greater masses compared to the volume of those substances whereas substances with low densities have greater volume compared to their masses.
The volume of the solid block = 78 * 55 * 35 = 150150 cm³
mass of solid block = 569 g
Density of the solid block = 569 g/150150 cm³
Density of the solid block = 3.79 * 10⁻³ g/cm³
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Please help me, I can't figure this out. You have a 450.0 mL balloon filled with 0.0184 moles of Helium gas. The volume of the balloon will change, but the pressure of the gas inside will always match the 1.00 atm pressure outside. If the balloon is kept at a constant 25oC, how many moles of gas must you remove to shrink the balloon down to 200.0 mL?
Answer and Explanation:
V1/n1 = V2/n2
450.0 mL / 0.0184 mol = 200.0 mL / n2
n2 = 8.17X10^-3 mol
moles removed = 0.0184-8.17X10^-3 = 0.0102 mols removed, I think I'm right but I'm not 100% sure..
According to Avogadro's law, 0.008 moles of gas must be removed to shrink balloon to 200 ml.
What is Avogadro's law?Avogadro's law is a gas law which states that the total number of atoms or molecules has a direct proportion to the volume occupied by a gas at a constant temperature and pressure.
It is closely related to ideal gas equation as it links temperature, pressure, volume and the amount of substance.It is given as, V∝n,
The straight line graph of volume versus moles is a straight line passing through the origin which implies that zero moles of gas occupy zero volume.
Here, the number of moles is calculated as, V₁/n₁=V₂/n₂
Therefore on substitution, n₂=0.0184×200/450=0.008 moles.
Thus,0.008 moles are required to shrink the balloon to 200 ml.
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What is the total number of peaks due to singly charged ions in the complete mass
spectrum of chlorine, Cl2
?
A Two
B Three
C Four
D Five
Five is the total number of peaks due to singly charged ions in the complete mass spectrum of chlorine, \(Cl_{2}\)
How many peaks do \(Cl_{2}\)'s molecular ions have?
The mass spectra of compounds with a single chlorine atom show two molecular ion peaks. This is because there are two isotopes of chlorine, 35Cl and 37Cl.
The molecular ion and fragment ions will both have peaks in the mass spectrum. When a mass spectrum is interpreted, a specific molecule can be located, confirmed, or its quantity can be calculated. the base summit of a mass spectrum's tallest (strongest) peak, caused by the ion with the highest relative abundance
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Five is the total number of peaks due to singly charged ions in the complete mass spectrum of chlorine, \(Cl_{2}\).
How many peaks do 's molecular ions have?
The mass spectra of compounds with a single chlorine atom show two molecular ion peaks. This is because there are two isotopes of chlorine, 35Cl and 37Cl.
The molecular ion and fragment ions will both have peaks in the mass spectrum. When a mass spectrum is interpreted, a specific molecule can be located, confirmed, or its quantity can be calculated. the base summit of a mass spectrum's tallest (strongest) peak, caused by the ion with the highest relative abundance
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Why does boron not react directly with hydrogen
Answer:
that's a good question but I'm not too sure
Identify the substance that has formula mass of 133.5amu.
(a) MgCI
b)SCI
c)BCI
D) AICI
The calculated formula masses to 133.5 amu, we find that the substance with a formula mass closest to 133.5 amu is (d) AlCl3. Therefore, the answer is option D.
To identify the substance with a formula mass of 133.5 amu, we need to calculate the formula mass of each given substance and compare it to 133.5 amu.
(a) MgCl2:
The formula mass of MgCl2 can be calculated by adding the atomic masses of magnesium (Mg) and chlorine (Cl).
Mg: atomic mass = 24.31 amu
Cl: atomic mass = 35.45 amu
Formula mass of MgCl2 = (24.31 amu) + 2(35.45 amu) = 95.21 amu
(b) SCl:
The formula mass of SCl can be calculated by adding the atomic masses of sulfur (S) and chlorine (Cl).
S: atomic mass = 32.07 amu
Cl: atomic mass = 35.45 amu
Formula mass of SCl = 32.07 amu + 35.45 amu = 67.52 amu
(c) BCl:
The formula mass of BCl can be calculated by adding the atomic mass of boron (B) and chlorine (Cl).
B: atomic mass = 10.81 amu
Cl: atomic mass = 35.45 amu
Formula mass of BCl = 10.81 amu + 35.45 amu = 46.26 amu
(d) AlCl3:
The formula mass of AlCl3 can be calculated by adding the atomic mass of aluminum (Al) and 3 times the atomic mass of chlorine (Cl).
Al: atomic mass = 26.98 amu
Cl: atomic mass = 35.45 amu
Formula mass of AlCl3 = 26.98 amu + 3(35.45 amu) = 133.78 amu. Option D
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Need help please don’t understand
Salt hydrolysis refers to the interaction of salt cations or anions with water to produce acidic or basic solutions.
What is salt hydrolysis?Salt hydrolysis is the process by which salts are dissolved in water to form either basic or acidic solutions.
Considering the hydrolysis of the given salts, the net-ionic equations, expressions for the equilibrium constants (Ka or Kb), and values of Ka or Kb for the given solutions are as follows:
The 0.1 M NaC₂H₃O₂:
Net-ionic equation: CH₃COO⁻ + H₂O ⇌ CH₃COOH + OH⁻
Expression for equilibrium constant: Ka = [CH₃COOH][OH⁻] / [CH₃COO-]
Value of Ka: 1.8 × 10⁻⁵
0.1 M NH₄CI:
Net-ionic equation: NH₄⁺ + H₂O ⇌ NH₃ + H₃O⁺
Expression for equilibrium constant: Kb = [NH₃][H₃O⁺] / [NH₄⁺]
Value of Kb: 5.6 × 10⁻¹⁰
0.1 M ZnCl₂:
ZnCl2 does not undergo hydrolysis since it is a neutral salt.
0.1 M KAl(SO₄)₂:
KAl(SO₄)₂ does not undergo hydrolysis since it is a neutral salt.
0.1 M Na₂CO₃:
Net-ionic equation: CO₃²⁻ + H₂O ⇌ HCO₃⁻ + OH⁻
Expression for equilibrium constant: Kb = [HCO₃⁻][OH⁻] / [CO₃²⁻]
Value of Kb: 2.3 × 10⁻⁴
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A new element was recently discovered. It is called Jurupium and has a molar mass of 125 grams/mole. How many moles of Jurupium are in 375 grams of Jurupium metal?
In 375 grammes of the metal Jurupium, there are 3 moles of the element.
How did element 99 get its name?On 1 November 1952, the first thermonuclear explosion, which occurred on a Pacific atoll, left behind debris that contained the element Einsteinium. A neighbouring atoll's fallout material was shipped to Berkeley, California, for analysis. It belongs to the group of elements with atomic number 63 that are numerically squeezed between barium and hafnium. A lanthanide, or europium, is one of those mysterious elements outside the periodic table's core.
Divide the mass of Jurupium by its molar mass to see how many moles there are in 375 grammes of Jurupium metal:
375 g / 125 g/mol = 3 moles
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pliz, answer my this all question
A state in the United States where the mining of metal ores is a large part of the economy is looking at the future of the industry. The state's
governor appoints a commission to determine if state funds should be used to continue supporting mining or to expand metal recycling
programs in the state. The commission evaluates two proposed plans based on the ratings of five criteria on a scale from one to ten, where a
higher number indicates the criterion is better met. The table shows the criteria and ratings for each plan.
Purpose
and Plan
Mining plan
Recycling
plan
Increasing tax
revenue for the state.
6
3
Increasing the number
of jobs in the state.
5
6
Decreasing
damage to habitat
2
9
Decreasing waste
in landfills
2
8
Producing a favorable
cost-benefit analysis
7
6
The state governor tells the commission to select the plan that best meets the ratings goal for these criteria: increasing the number of jobs,
decreasing damage to habitat, and producing a favorable cost-benefit analysis. Use the menus to complete the sentence.
The commission should select the
plan because it has the higher rating for
The decision-making process, also known as the evaluation process, is the process of choosing a strategy based on predetermined criteria.
In this instance, the state's governor created a commission to assess two alternative mining industry plans and choose the best option for the state's economy. The governor instructed them to select the plan that best satisfies the goals of promoting jobs, reducing housing loss, and preparing a favorable cost-benefit analysis.
The commission evaluated the two designs on the basis of five factors. Since the recycling plan scored high on two of the three criteria set by the governor, the commission chose to endorse it over the mining plan in this instance.
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How many water molecules are found within the crystalline structure of one hydrate molecule?
What is the molecular formula of the hydrate?
Attached my worksheets to it and the questions
a. The Mass of water driven off = 0.15 g
b. Moles of anhydrate = 0.00257 moles
c. Moles of water driven off is 0.00833 moles
d. There are 3 moles of water within the crystalline structure of one molecule of the hydrated salt.
e. The molecular formula of the hydrated salt will be X.3H₂O
What is the mass of water driven off from the hydrated salt?a. The mass of water driven off from the hydrated salt is:
Mass of water driven off = 0.5 g - 0.35 g
Mass of water driven off = 0.15 g
b. Molecular mass of salt = 136 g/mol
moles of anhydrate = 0.35/136
Moles of anhydrate = 0.00257 moles
c. Moles of water driven off = mass/molar mass
molar mass of water = 18 g/mol
Moles of water driven off = 0.15/18
Moles of water driven off = 0.00833 moles
d. Moles of water within the crystalline structure of one molecule of the hydrated salt is determined by converting to whole number mole ratio by dividing with the smallest ratio,
Salt to water ratio = 0.00257 /0.00257 : 0.00833/0.00257
Salt to water ratio = 1 : 3
Therefore, there are 3 moles of water within the crystalline structure of one molecule of the hydrated salt.
e. Assuming the anhydrous salt is X, the molecular formula of the hydrated salt will be X.3H₂O
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Please please !!! help me I’ve been doing this for 2 hours
How many molecules of NaCl are in 0.61 moles of NaCl?
1.8 x 1023
2.5 x 1023
3.7 x 1023
4.5 x 1023
Answer:
3.7 x 10^23
is the right answer
What are the non-living things that make up an ecosystem?
Answer:
abiotic things
abiotic things aren't living
Answer:
The non-living things would be the soil, rocks, and water. There are other things, but those are the main ones.