What happens when a chemical hand warmer is unwrapped and starts to work?
A. A physical change absorbs thermal energy.
B. A chemical reaction absorbs thermal energy.
C. A physical change releases thermal energy.
D. A chemical reaction releases thermal energy.
Answer: D. A chemical reaction releases thermal energy.
Explanation:
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please help !!!!!!!!!!!!!!!!
Answer:
covalen and ionic compound
Determine the mass of the negative electrode at the start of the experiment use figure 3
What four factors influence the rate of a homogeneous reaction.
Reactant concentration, the physical state of the reactants, surface area, temperature, and the presence of a catalyst are the four factors to influence the rate of a homogeneous reaction.
What is rate of reaction ?The term rate of reaction is defined as the speed at which a chemical reaction takes place. It is also defined as proportional to the increase in the concentration of a product per unit time and to the decrease in the concentration of a reactant per unit time.
Surface area, greater surface area, more collisions are available and then concentration, when increase the concentration then increase the likelihood of reactants colliding. Catalysts increase reaction without itself getting used up.
Thus, The factors to influence the rate of a homogeneous reaction are Reactant concentration, the physical state of the reactants, surface area, temperature, and the presence of a catalyst.
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Which statement describes a chemical property of mercury?
A. Mercury bonds with oxygen to form a compound found in some
batteries.
B. Mercury is the only metal that is liquid at room temperature.
C. Mercury is much denser than water, so it will sink in water.
D. Mercury is a shiny, silver substance that is found in some
thermometers.
Answer:
It's A
Explanation:
I took the test. For A p e x
What is potential energy?
Answer:
Potential energyPotential energy is the energy possessed by an object because of its position with respect to a reference.
Explanation:
The energy obtained because of its location or position is called potential energy.
》Example:
Water in a dam stores potential energy because of its height.
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°• Answer By Yoland •°
transition elements have variable valency why
Answer:
The transition elements have their valence electrons in two different sets of orbitals that are (n-1)d and ns. Thus, transition elements show variable valencies due to the involvement of penultimate d shell electrons.
Explanation:
i need help with number 1 :/ please help me, thank you
Answer:
Amplitude is measured from the center line to the highest point in the waves.
Wavelength is the distance between one wave to the other from the highest point.
Frequency is the rate of the waves.
Compare blue and violet light. which one has the highest energy?
Longest wavelength?
Answer:
Blue
Explanation:
Blue would have the longest wave length because following ROY G BIV the wave length distance between the two decreases as you move from Red to Violet.
Rank lead, phosphorus, and barium in order of increasing ionization energy.
Answer:
D) Ba < Pb < P
Explanation:
Barium (Ba): 5,2117
Lead (Pb): 7,4167
Phosphorus (P): 10,4867
please help , i’m doing a test and i’m really bad at science , lol , thank you !
it cannot be passed to the next generation meaning A chromosome will be eliminated
PLEASE HELP
Which of the following is a testable scientific question?
Do blue M&Ms taste better than green M&Ms?
1.What is beneath the ground on planets outside our solar system?
2.How does the age of city affect the number of trees in the city?
3.How many houses are in my neighborhood?
help me match the cards because there is a lot ill add more points please and thank you
Answer:
thats alot and makes no since
What is the formula unit for a compound made from Pb4+ and oxygen? (3 points)
PbO2
O2Pb
Pb4O2
O4Pb2
The formula unit of compound made up from Pb4+ and oxygen is PbO2.
The formula unit for a compound made from Pb⁴⁺ and oxygen is PbO₂. Therefore, option (1) is correct.
What is the formula unit?A formula unit represents the lowest whole number ratio of ions in an ionic compound. The formula mass of a substance is the sum of the atomic masses of the ions present in the formula unit of an ionic compound.
Formula unit is the empirical formula of any covalent or ionic solid compound which is used as an independent entity for stoichiometric calculations. Formula mass is also defined as the sum of atomic masses of constituent atoms in an ionic compound.
A molecule is made up of two or more elements that are covalently bonded. Also, the molecular mass gives the mass of a molecule relative to that of a carbon twelve atom which has a mass of twelve units.
As we know the valency of lead is 4 and the valency of oxygen is 2. To satisfy the valency of each other two oxygen combine with one lead (IV). Therefore, the formula unit of the compound is PbO₂.
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Importance of iron metals ions in biological System
Answer:
Metal ions are fundamental elements for the maintenance of the lifespan of plants, animals and humans. Their substantial role in biological systems was recognized a long time ago. They are essential for the maintenance of life and their absence can cause growth disorders, severe malfunction, carcinogenesis or death
Explanation:
:)
When 0. 25 g of the organic compound naphthalene are burned in a bomb calorimeter, the temperature of the water in the calorimeter increases from 24. 00°C to 26. 43 °C. The calorimeter's heat capacity is 4. 13 kJ/°C. How much heat (q_{rxn}) in kilojoules is released by the combustion of the naphthalene?.
-2.5089 kJ is the amount of heat is released by the combustion of the naphthalene.
How we calculate the released heat?Released amount of heat is calculated by using the below formula:
Q = -mcΔT, where
m = mass of naphthalene = 0.25g
c = specific heat of calorimeter = 4.13 kJ/°C
ΔT = change in temperature = 26.43°C - 24°C = 2.43°C
Putting all these values in the above equation, we get
Q = - (0.25 × 4.13 × 2.43) = - 2.5089 kJ
Hence, - 2.5089 kJ heat is released.
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balancing chemical equations
A pile of feathers has a mass of 57 g and a volume of 300 mL. Calculate the density.
Find the density of a brick that has a mass of 57 g and a volume of 12 mL.
A sample has a mass of 15 g and a volume of 3 mL. Calculate the density.
[tex]density = \frac{mass}{volume} [/tex]
1. density = 57/300
= 0.19 g/ml
2. density = 57/12
= 4.75 g/ml
3. density = 15/3
= 5.0 g/ml
how can hot water freeze faster then cold water.
Answer:
With the cooler water at the bottom, this uneven temperature distribution creates convection currents that accelerate the cooling process. Even with more ground to cover to freeze, the temperature of the hotter water can drop at a faster rate than the cooler water.
Explanation:
the neutralization reaction gets its name from.the fact that the products of the reaction are
Answer:
Neutral
Explanation:
Neutralization reaction gets its name from the fact that the products of the reaction are _____.
neutral
What is one key physical difference between transition
metals and poor metals?
А.Atomic mass
B.Hardness
C.Reactivity
D.Charge
Which substance is a heterogeneous mixture
Answer:
Is there any options?
Explanation:
A ball moving at a 7.0 m/s has a momentum of 98 kg•m/s. What is the ball's mass?
Answer:
Explanation:
Momentum has the formula of kg m/s and is represented by m*v
Formula
momentum= mv
Givens
m =??
v = 7 m/s
mv = 98 kg m/s
Solution
98 = 7 * m
98/7 = m
m = 14 kg
What is the cause of rejection of classical concept of oxidation and reduction reaction?
Answer:
Oxidation is the loss of electrons or an increase in the oxidation state of an atom, an ion, or of certain atoms in a molecule. Reduction is the gain of electrons or a decrease in the oxidation state of an atom, an ion, or of certain atoms in a molecule.
Explanation:
To solve such this we must know the concept of redox reaction. Therefore, The cause of rejection of classical concept of oxidation and reduction reaction is in any process, oxidation can occur only if reduction is also taking place side by side and vice versa.
What is chemical reaction?Chemical reaction is a process in which two or more than two molecules collide in right orientation and energy to form a new chemical compound. The mass of the overall reaction should be conserved. There are so many types of chemical reaction reaction like combination reaction, double displacement reaction.
Oxidation and reduction reaction involves gain of electron and loss of electron simultaneously. This type of reaction is called redox reaction. The cause of rejection of classical concept of oxidation and reduction reaction is in any process, oxidation can occur only if reduction is also taking place side by side and vice versa.
Therefore, the cause of rejection of classical concept of oxidation and reduction reaction is in any process, oxidation can occur only if reduction is also taking place side by side and vice versa.
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Which sentence explains why gases can change volume but liquids cannot?
A. Gravity affects liquid atoms more than gas atoms.
B. The forces holding atoms together are stronger in a liquid than in
a gas.
O c. The forces holding a liquid together are more flexible than those in
a gas.
D. Liquid atoms are more like solid atoms than gas atoms.
Answer:
B. The forces holding atoms together are stronger in a liquid than in
a gas
I hope that this helps!
PLS HELP ASAP IM MARKING BRAINLIEST. This is science
Answer:
Random
Explanation:
Materials have numerous domains. Domains have a north and south side. In magnetic metals, all of the domains are pointed in the same direction. This creates an overall magnetic field that gives the material its magnetic property.
On the other hand, non-magnetic materials still have domains but they don't face the same direction. Instead, they are randomly directed. This means that the material cannot have the same magnetic properties that ferromagnetic materials have.
What will a cathode ray do if a positive electrode is placed near the beam?
Answer:
The function of the cathode ray tube is to convert an electrical signal into a visual display. Cathode rays or streams of electron particles are quite easy to produce, electrons orbit every atom and move from atom to atom as an electric current.
Consider the reaction below. upper c upper c l subscript 5 (g) double-headed arrow upper p upper c l subscript 3 (g) plus upper c l subscript 2 (g). at 500 k, the reaction is at equilibrium with the following concentrations. [pci5]= 0.0095 m [pci3] = 0.020 [ci2] = 0.020 m what is the equilibrium constant for the given reaction? 0.042 0.42 2.4 24
The equilibrium constant for the given reaction is 0.0421.
What is equilibrium constant?Equilibrium constant of any reaction is define as the ration of the product of concentration of products to the product of the concentration of reactants, with raise to the respective coefficients.
Given chemical reaction is:
PCl₅ → PCl₃ + Cl₂
The equilibrium constant's for this reaction is:
Kc = [PCl₃] [Cl₂] / [PCl₅], where
Concentration of [PCl₃] = 0.020M
Concentration of [Cl₂] = 0.020M
Concentration of [PCl₅] = 0.0095M
Putting all these values in the above equation we get,
Kc = (0.02 x 0.02) / 0.0095 = 0.0421
Hence, 0.0421 is the equilibrium constant.
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Answer:
A on edg
Explanation:
im doin it rn
Which of the following are NOT SAFE things to do, as we might get an electric shock?
1) Touching the switch of a geyser with dry hand.
2) Standing on a wooden stool to check a plug point.
3) Poking a metal rod into an electrical socket.
4) Touching the water in which an immersion heater is kept.
Plz solve anyone...........................
Answer:
no (units don't cancel each other out)
yes (convert both to same unit and multiply)
yes (multiply)
Explanation: