1. Q=112.8 kJ
2. Q=5.01 kJ
Further explanationThe heat required for phase change :
melting/freezing :Q = mLf
Lf=latent heat of fusion
vaporization/condensationQ = mLv
Lv=latent heat of vaporization
1.
m=50 g=0.05 kg
Lv (water) = 2256 kJ/kg
[tex]\tt Q=0.05\times 2256=112.8~kJ[/tex]
2.
m=15 g=0.015 kg
Lf for water = 334 kj/kg
[tex]\tt Q=0.015\times 334=5.01~kJ[/tex]
what percent of a sample of a radioactive element whose half life=5.0 years will decay after 25 years?
Answer:
Calculate the rate of decay constant for U-238 if its half-life is 4.468 × 109 years. Answer: If the problem is referring to the half-life, then the ratio of = 0.5 because half of the original sample has already undergone decay.
Explanation:
which element has a higher atomic number of aluminum or oxygen
Answer:
aluminum
Explanation:
oxygen's atomic number is 8.
aluminum's atomic number is 13.
Arrange the elements in order of increasing ionization energy. Use the
periodic table to identify their positions on the table.
Drag each tile to the correct box.
Hola
Tiles
chlorine
fluorine
gallium
phosphorus
Sequence
Answer:
Gallium - Phosphorous - Fluorine - Chlorine
Explanation:
Answer:
Gallium < Phosphorus < Chlorine < Fluorine
Explanation:
<3
Which molecule has the strongest forces of attraction between molecules?
Dipole-dipole interactions are the strongest intermolecular pressure of attraction.
Answer: Dipole-dipole interactions are the strongest intermolecular force of attraction.
Explanation:
An unbalanced chemical equation is shown:
2NaN3 → 2Na + N2
Which of the following statements explains why the equation is not balanced?
Four molecules of N2 should be produced during the decomposition.
Three molecules of N2 should be produced during the decomposition.
Four molecules of N2 should be produced during the synthesis reaction.
Three molecules of N2 should be produced during the synthesis reaction.
The correct statement is B. Three molecules of N₂ should be produced during the decomposition. :)
Answer: b
Explanation: I took the quiz
Is copper sulphate malleable?
Answer:
Yes, Copper (Cu) in its pure form is a reddish-brown metallic element with high ductility and malleability that is an excellent conductor of heat and electricity: atomic weight 63.54; atomic number 29; density 8.94 g/cm3; melting point 1083°C; and boiling point 2595°C.
Answer:
no ,its not malleable
Explanation:
copper II sulphate is a blue compound , which is brittle solid , crystalline .
copper metal is malleable and ductile
Explain why both a power source (like a battery) and a complete circuit are necessary for an electromagnet to function.
this is science homework by the way, please help me with it:)
Answer:
Electromagnets are only functional when electricity is passing through them. In other words, they only create a magnetic field when there is an electric current flowing.
A power source like a battery is therefore necessary to supply the electric current necessary for the magnet to work however, it will not work unless the circuit is closed as electricity cannot not flow in an open circuit because current needs to be able to flow from one end of a power source to the other end.
Explanation:
ha hot dog hamburger hamburger ng baboy hahaha bomba girl home baboy
What would be a reasonable pH level of the dish soap in your kitchen?
Answer:around 7
If your dish soap is labeled mild, gentle, or great for hands, chances are its pH level is somewhere right around 7. This mildness makes dish soap perfect for day to day cleaning. Most surfaces won't be damaged by dish soap, and there are a lot of places it can be used besides in the kitchen sink
Explanation: I have had this question before
Answer:
7
Explanation:
Considering that you use dish soap on a daily occurence... it is best for it to be versatile. By making it 7... it is very neutral.
This means it's not too acidic for some situations... nor is it too basic in other situations.
Use the equation below to solve the problem that follows.
2H2 (g) + O2 (g) → 2H2O (g)
When David reacts 13.8 grams of hydrogen gas with excess oxygen, 87.0 grams of water are formed. Calculate his percent yield of water.
Answer: 142.8%
Explanation:
13.8g H2 * (1 mol H2 / 2 g H2) * (2 mol H2O/ 2 mol H2) * (18 g H2O/1 mol H2O) = 124.2 g H2O
we just calculated our theoretical amount that should be formed and we are given the actual
percent yield: actual/theo * 100% = 124.2/87 * 100% = 142.8%
What is 13.48cm+7.6cm rounded to the correct number of significant figures?
When determining an element’s chemical properties, the most important subatomic particle to look at is
Answer:
Electrons
Explanation:
When determining the chemical properties of elements, the most important subatomic particle to consider is the electrons.
Electrons are negatively charged particles that orbits an atom. They occupy the extranuclear space of an atom.
These electrons determines the chemical properties of each atom. Most especially, the valence ones. All elements wants to resemble the noble gases, so they alter their number of electrons in order to attain this stable state.
Which compound is
ionic?
Answer:
chemistry
Explanation:
Use the equation below to solve the problem that follows.
2H2 (g) + O2 (g) → 2H2O (g)
When David reacts 13.8 grams of hydrogen gas with excess oxygen, 87.0 grams of water are formed. Calculate his percent yield of water.
Percent yield = 70%
Further eplanationPercent yield is the comparison of the amount of product obtained from a reaction with the amount you calculated
General formula:
Percent yield = (Actual yield / theoretical yield )x 100%
An actual yield is the amount of product actually produced by the reaction. A theoretical yield is the amount of product that you calculate from the reaction equation according to the product and reactant coefficients
Reaction
2H₂ (g) + O₂ (g) → 2H₂O (g)
mass of H₂O (theoretical) :[tex]\tt mass=mol\times MW(mol~ratio~H_2O\div H_2=2\div 2)\\\\mass=(\dfrac{2}{2}\times \dfrac{13.8}{2})\times 18~g/mol\\\\mass=124.2~g[/tex]
percent yield[tex]\tt \%yield=\dfrac{87}{124.2}\times 100\%=\boxed{\bold{70\%}}[/tex]
The theory of plate tectonics was, at first, rejected by most scientists. Now most geologists accept that tectonic plates exist and that these tectonic plates can and do move. What is responsible for the change in how scientists think about plate tectonics?
Answer:
The validation of seafloor spreading in the 1950s and 60s
Explanation:
The theory of seafloor spreading was supported by numerous evidence including thermal probes that showed that heat flow over the mid-ocean ridges measured up to four times those measured in general bottom sediments, which are taken as due to the presence of molten Earth material close to the ridge crest
The ridge crest also show signs unusually seismic wave velocities that are considered to be due to microfracturing and thermal expansion from upwelling magma
BEST ANSWER WILL BE MARKED BRAINIEST
Why does photosynthesis occur? Please explain your answer and do NOT google to find the answer.
Answer:
photosynthesis occurs so the plants can create energy from carbon dioxide and sunlight.
Explanation:
so basiclly it occurs so the plants can create energy to stay alive.
Answer:
Explanation:
photosynthesis occurs basically to help plants get light in order to produce its necessary daily production of nutrients needed for animals to get carbohydrates froms which is eaten by animals since it gives energy. so basically photosynthesis--> energy --> carbs for mammals to eat!
the green colour reflects off the plant so it is not absorbed by the chloroplasts rather all colours are absorbed just not green.
and every organic material on earth is produced by these cells which convert energy from the sun into nutrient filled plants.. its essential for the CO2 cycle , and since they conduct photo synthesis they are lowest level in the food chain so basically its important since they create nutrients for our plants.
The diagram below shows the distance traveled by two light waves in 1 second.
Based on the diagram, which of these conclusions is correct?
The frequency of Wave 1 is double the frequency of Wave 2.
The frequency of Wave 2 is double the frequency of Wave 1.
The wavelength of Wave 1 is four times the wavelength of Wave 2.
The wavelength of Wave 2 is four times the wavelength of Wave 1.
Please help
Answer:
The frequency of Wave 2 is double the frequency of Wave 1.
Explanation:
Waves with higher frequencies have shorter wavelengths, and lower frequencies have longer wavelengths.
What is one danger associated with the use of hydrogen gas
Answer:
Topping the list of concerns is hydrogen burns. In the presence of an oxidizer -- oxygen is a good one -- hydrogen can catch fire, sometimes explosively, and it burns more easily than gasoline does.
Answer:
hydrogen burns
hope it helps
What is filtration .
Will mark as brainliest
Answer:
the action or process of filtering something or in chemistry separating suspended solid matter from a liquid causing latter to pass through the pores is some substance
if you had a chance to get a scholarship abroad?what would you do?
Answer:
I Would bc it's the better opportunity
How many Joules of heat are needed to melt 3.0 g of ice?
Answer:A substance must absorb heat energy so that it can melt or boil. The temperature of the substance does not change during melting, boiling or freezing - even though energy is still being transferred
Explanation:imm not sure
What is the mass of one electron in grams if an electron has the charge of
-1.6022 x 10-19C and lg = -1.76 x 108 C.
The mass of one electron : 9.103 x 10⁻²⁸ g
Further explanationElectrons are a part of the atomic nucleus particles (including protons and neutrons), and are negatively charged (-1)
An electron has the charge of -1.6022 x 10⁻¹⁹C
1 g = -1.76 x 10⁸ C
so the mass of one electron :
[tex]\tt \dfrac{1.6022\times 10^{-19}}{1.76\times 10^8}=9.103\times 10^{-28}~g[/tex]
Predict the products for the following chemical reaction: H2 + O2 →
a. H30
b. H20
c. H2OH
d. OH + OH
O a
please someone help me its due today thanks :D
Answer:
D
Explanation:
All of the above are great examples!
"Endothermic reactions are those which absorb heat during the reaction."
Ian uses litmus paper to determine whether five unknown solutions are acids or bases. The litmus paper turns red when the pH is 4.5 or below and blue when the pH is 8.2 or above. Ian records the results in the data table.
Ian accidentally spills a beaker of an unknown solution. It splashes onto the strip he used to test Solution 1, and the strip turns from red to blue. Based on this observation, which conclusion could Ian make about the solution that he spilled?
Answer: b
explanation: i had the question on a test and got it right.
8)How many grams are in 0.02 moles of beryllium iodide, BeI2?
9)How many moles are in 68 grams of copper (II) hydroxide, Cu(OH)2?
10)How many grams are in 3.3 moles of potassium sulfide, K2S?
11) How many grams are in 2.3 x 10-4 moles of calcium phosphate, Ca3(PO3)2?
Answer:
0.03:---$7--$-$7$--$-$-$$-$+-$$7-$$-$7-$8$+$-$
Which container has gas stored at the highest temperature
Answer: 3
Explanation:
Answer:
kinetic energy
Explanation:
may be iam not sure
How do scientist respond to experimental observations that don’t match current theories?
Answer: The results of the experimental observations should coincide with the facts of the current theories.
Explanation:
The scientific theory can be defined as the well defined as supported explanation for a natural phenomena. It is based upon the facts observed and also supported by the evidences obtained from the experimental trials.
If the experimental observations do not match with the concept of current scientific theory then the scientific either perform the experiment with the same scientific methodology or can switch to another scientific methodology to satisfy the facts of the current theories.
HELPP!!! ASAP!!!! BRAINLIEST!!!
Complete the following sentences. Energy is required to _______ bonds in a molecule and released when bonds are _______.
Answer:
Energy is required to break bonds in a molecule and released when bonds are made.
Explanation:
Energy is added to break bonds and released when making bonds.
A balloon filled with helium floats in the air. What does this tell you about the density of helium?
Answer:
helium is denser than air
Answer:
For air, which has a molar mass of 29.0 g/mol, this gives a density of 1.18 g/l. Helium, which has a mass of 4.00 g/mol, has a density of 0.164 g/l.
Identify the number of electrons
Atomic mass: 24
Atomic number: 12
-2 charge
Answer:
24 is the answer of this question