2H2O + 2Na ? 2NaOH + H2 Which of these is a reactant in this chemical reaction?

Answer is: the mass of a sample of aluminum is  9.45 grams.

ΔT = 100.1°C - 30.0°C.

ΔT = 70.1°C.; change in temperature of a sample of aluminium.

Cp(Al) = 0.900 J/g·°C; specific heat capacity for aluminium.

Q = 596 J; heat absorbed.

Q = m(Al) · ΔT · Cp(Al).

m(Al) = Q ÷ (ΔT · Cp(Al)).

m(Al) = 596 J ÷ (70.1°C · 0.900 J/g·°C).

m(Al) = 9.45 g; mass of aluminium sample.

water and carbon dioxide

Answer:  C. atoms must be small.

Explanation:  Hydrogen bond is the result of the electrostatic forces of attraction between the hydrogen and the electonegative atom. It is a type of dipole dipole interaction which is not so much of a covalent bond.

The options A, B and D satisfies the definition of the hydrogen bonding but the option C seems to be irrelevant as hydrogen bonding does not deal with the size of the atom.

Thus for the hydrogen bonding , the other atom must be electronegative, and atoms must have atleast one lone pair of electrons and atoms must not be able to closely approach the hydrogen.

Frequency of photon = is 6.85 X 10¹⁴ sec⁻¹

Energy of photon , E = hv

where h is Planck's constant, v is the frequency of photon

E = 6.63 × 10⁻³⁴ J.s x 6.85 X 10¹⁴ s⁻¹

E = 4.54 x 10⁻¹⁹ J

Therefore, the energy of a photon of green light is 4.54 x 10⁻¹⁹ J.

Answer:

The quantity 10 m/s is the only vector quantity because it is a measurement that includes a direction.

Explanation:

Vector quantities are physical quantities with both magnitude (size) and direction. Examples of vectors include displacement, velocity, acceleration, force, momentum etc.

Time is a scalar quantity having only  size. So 10 s is not a vector. 10 m/s forwards is velocity because of the direction.

the general principle or theory is probably false

Answer:They exist at specific energy levels.

Explanation:

Hey there!

Molar mass NaCl = 58.44 g/mol

Number of moles

n =  mass of solute / molar mass

n = 59.76 / 58.44

n = 1.0225 moles of NaCl

Volume in liters:

270 mL / 1000 => 0.27 L

Therefore:

M = number of moles / volume ( L )

M = 1.0225 / 0.27

= 3.78 M

Hope that helps!

When solid copper(II) nitrate is dissolved in water, it breaks down into copper(II) ions and nitrate ions. This process is represented by the balanced chemical equation: Cu(NO3)2 (s) -> Cu^2+ (aq) + 2 NO3^- (aq).

When solid copper(II) nitrate, denoted as Cu(NO3)2, is put into water, it dissociates into its ions. The balanced chemical reaction is represented as follows:

Cu(NO3)2 (s) -> Cu^2+ (aq) + 2 NO3^- (aq)

Here, (s) stands for solid, while (aq) means aqueous, i.e., ions dissolved in water. Copper(II) nitrate breaks down into copper(II) ions (Cu^2+) and nitrate ions (NO3^-). Because copper(II) nitrate is a strong electrolyte, it dissociates completely in water, meaning there are no leftover solid particles floating in the solution, just a solution of the individual ions.

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Answer: Groundwater that forms caves because it is slightly acidic.

Explanation:

The water under the ground present inside the cracks and spaces in sand, soil and rocks is called ground water.

When ground water moves through the soil it results in the formation of acid. Further, this acid helps minerals to get dissolve. These minerals get deposited on other places as well.

This process of deposition and erosion helps in the formation of caves.

Thus, it can be concluded that groundwater that forms caves because it is slightly acidic.

Q: The recommended daily allowance of selenium in your diet is 6.97x10-7 mole. How many atoms of selenium is this?

                  4.19 × 10¹⁷ Se Atoms

                     As we know that 1 mole of any substance contains exactly 6.022 × 10²³ particles which is also called as Avogadro's Number. So in order to calculate the number of particles (atoms) contained by 6.97 × 10⁻⁷ moles of Se, we will use following relation,

           Moles  =  Number of Atoms ÷ 6.022 × 10²³ Atoms.mol⁻¹

Solving for Number of Atoms,

           Number of Atoms  =  Moles × 6.022 × 10²³ Atoms.mol⁻¹

Putting values,

           Number of Atoms  =  6.97 × 10⁻⁷ mol × 6.022 × 10²³ Atoms.mol⁻¹

           Number of Atoms  =  4.19 × 10¹⁷ Atoms

++++++++++++++++++++++++++++++++++++++++++++++++++

Q: A bracelet containing 0.200 mol metal is 75% gold. How many atoms of gold are in the bracelet?

                  9.033 × 10²² Atoms of Gold

                     As we know that 1 mole of any substance contains exactly 6.022 × 10²³ particles which is also called as Avogadro's Number. So in order to calculate the number of particles (atoms) contained by 0.200 moles of Au, we will use following relation,

           Moles  =  Number of Atoms ÷ 6.022 × 10²³ Atoms.mol⁻¹

Solving for Number of Atoms,

           Number of Atoms  =  Moles × 6.022 × 10²³ Atoms.mol⁻¹

Putting values,

           Number of Atoms  =  0.200 mol × 6.022 × 10²³ Atoms.mol⁻¹

           Number of Atoms  =  1.20 × 10²³ Atoms

For 75%,

           Number of Atoms  =  1.20 × 10²³ Atoms × 0.75

           Number of Atoms  =  9.033 × 10²² Atoms of Gold

++++++++++++++++++++++++++++++++++++++++++++++++++

Q: Which has more atoms, 10.0 g C or 10.0 g of Ca? How many atoms does each contain?

               Carbon has greater number of Atoms.

Data Given:

                 Mass of Carbon =  10 g

                 M.Mass of Carbon  =  12.01 g.mol⁻¹

                 Mass of Calcium =  10 g

                 M.Mass of Calcium  =  40.08 g.mol⁻¹

Step 1: Calculate Moles of Carbon as,

                 Moles  =  Mass ÷ M.Mass

Putting values,

                 Moles  =  10 g ÷ 12.01 g.mol⁻¹

                 Moles  =  0.8326 mol

Step 2: Calculate number of Carbon atoms,

As 1 mole of any substance contains 6.022 × 10²³ particles (Avogadro's Number) then the relation for Moles and Number of Carbon atoms can be written as,

                 Moles  =  Number of C Atoms ÷ 6.022 × 10²³ Atoms.mol⁻¹

Solving for Number of C atoms,

                 Number of C atoms  =  Moles × 6.022 × 10²³ Atoms.mol⁻¹

Putting value of moles,

                 Number of C atoms  =  0.8326 mol × 6.022 × 10²³ Atoms.mol⁻¹

                 Number of C atoms =  5.01 × 10²³ C atoms

Step 3: Calculate Moles of Calcium as,

                 Moles  =  Mass ÷ M.Mass

Putting values,

                 Moles  =  10 g ÷ 40.08 g.mol⁻¹

                 Moles  =  0.25 mol

Step 4: Calculate number of Calcium atoms,

As 1 mole of any substance contains 6.022 × 10²³ particles (Avogadro's Number) then the relation for Moles and Number of Calcium atoms can be written as,

                 Moles  =  Number of Ca Atoms ÷ 6.022 × 10²³ Atoms.mol⁻¹

Solving for Number of Ca atoms,

                 Number of Ca atoms  =  Moles × 6.022 × 10²³ Atoms.mol⁻¹

Putting value of moles,

                 Number of Ca atoms  =  0.25 mol × 6.022 × 10²³ Atoms.mol⁻¹

                 Number of Ca atoms =  1.50 × 10²³ C atoms

++++++++++++++++++++++++++++++++++++++++++++++++++

Q: A mixture contains 0.250 mol Fe and 1.20 g C. What is the total number of atoms in the mixture?

                 2.10 × 10²³ Atoms in Mixture

Atoms in Fe:

                  As we know that 1 mole of any substance contains exactly 6.022 × 10²³ particles which is also called as Avogadro's Number. So in order to calculate the number of particles (atoms) contained by 0.25 moles of Fe, we will use following relation,

           Moles  =  Number of Atoms ÷ 6.022 × 10²³ Atoms.mol⁻¹

Solving for Number of Atoms,

           Number of Atoms =  Moles × 6.022 × 10²³ Atoms.mol⁻¹

Putting values,

           Number of Molecules  =  0.25 mol × 6.022 × 10²³ Atoms.mol⁻¹

           Number of Molecules  =  1.50 × 10²³ Atoms of Fe

Atoms in C:

Step 1: Calculate Moles of Carbon as,

                 Moles  =  Mass ÷ M.Mass

Putting values,

                 Moles  =  1.20g ÷ 12.01 g.mol⁻¹

                 Moles  =  0.0999 mol

Step 2: Calculate number of Carbon atoms,

As 1 mole of any substance contains 6.022 × 10²³ particles (Avogadro's Number) then the relation for Moles and Number of Carbon atoms can be written as,

                 Moles  =  Number of C Atoms ÷ 6.022 × 10²³ Atoms.mol⁻¹

Solving for Number of C atoms,

                 Number of C atoms  =  Moles × 6.022 × 10²³ Atoms.mol⁻¹

                 Number of C atoms  =  0.0999 × 6.022 × 10²³ Atoms.mol⁻¹

                 Number of C atoms  =  6.01 × 10²² C Atoms

Total Number of Atoms:

  =  6.01 × 10²² C Atoms + 1.50 × 10²³ Atoms of Fe

  =  2.10 × 10²³ Atoms in Mixture

Remaining answers are attached.

The formula is molarity (M) = moles / liters

molarity (M) = ?

1/ mass = 36.52 g of KCl (you need to find the mole)

mole = mass / Molar mass

Molar mass of KCl:

K = 39.10 g/mol

Cl = 35.45 g/mol

Add K and Cl together: 39.10 + 35.45 = 74.55 g/mol

mole = 36.52 g of KCl / 74.55 g/mol

mole = 0.489 mol of KCl

2/ Volume = 820 mL ( you need to convert to L)

820 / 1000 = 0.82 L

=> M = mol / L

    M = 0.489 mol / 0.82 L

    M = 0.59 mol/L

Hope this help!

Answer: 0.27 M

Explanation:

Molarity of a solution is defined as the number of moles of solute dissolved per liter of the solution.

[tex]Molarity=\frac{n\times 1000}{V_s}[/tex]

where,

n = moles of solute

To calculate the moles, we use the equation:

[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}=\frac{36.52g}{166g/mol}=0.22moles[/tex]

[tex]V_s[/tex] =volume of solution in ml

Molarity =[tex]\frac{0.22\times 1000}{820ml}=0.27M[/tex]

The molarity of the solution is 0.27 M.

You know what number of significant figures is required by what they give you originally. In this case, there is only one. (3x10^4)(4x10^23) = 1.2x10^28. However, this is the answer with two significant figures. Thus, round it to become one sigfig: 1x10^28.

Answer:

1x10^28

Explanation:

The correct answer is option A and B

About 300 B.C., Aristarchus suggested that the sun was at the center of the universe because a) the brightness of the planets would change and b) the planets appeared to move among the constellations.

18 centuries before  Copernicus, Aristarchus predicted that  all planets orbit the sun. In other words, he suggested the Solar System is heliocentric.

Answer:

the answer is A And B

Explanation:

just took the test

Hi Khal75,

Experiment: How to seperate iron fillings

Iron fillings is a substance that attracts to magnets.

Answer - Separated using a magnet; magnetism

If you move a magnet around different solids with the iron fillings in it, it wil attract the iron to be able to seperate it.

Classify each of the following materials as a pure substance or mixture. If it is a pure substance, indicate if it is an element or a compound. If it is a mixture, indicate if it is a homogeneous mixture or heterogeneous. (2 points each)

Questions

1.  

The copper in a copper wire  pure

2.

Gatorade  heterogeneous

3.  

Chocolate chip ice cream    heterogeneous

4.  

Sugar (C12H22O11)   pure

5.  

Glitter nail polish   heterogeneous

6.

Diamond (C)   pure

7.  

Salt (NaCl)  pure

8.  

Air  homo

9.  

Helium gas  pure

10.  

Carbon dioxide gas  pure

11.

Coffee  depends on being black and unsaturated

12.  

Caffeine (C8H10N4O2)   pure

13.  

Tomato soup  heterogeneous

14.

Chicken noodle soup heterogeneous

15.  

Brass  homo

16.  

Pure water  pure

17.  

Pure iron  pure

18.  

Sweat  homo

19.  

Baking soda (NaHCO3)  pure

Final answer:

Detailed classification of substances as pure substances or mixtures, elements or compounds, and homogeneous or heterogeneous mixtures.

Explanation:

A pure substance either consists of a single type of atom, an element, or of molecules made from atoms of two or more types bound together, known as compounds. Mixtures can be either homogeneous, where the composition is consistent throughout, or heterogeneous, where the substances that make up the mixture are not evenly distributed. The items can be classified as -

1. The copper in a copper wire: Pure substance - Element

2. Gatorade: Mixture - Homogeneous

3. Chocolate chip ice cream: Mixture - Heterogeneous

4. Sugar (C12H22O11): Pure substance - Compound

5. Glitter nail polish: Mixture - Heterogeneous

6. Diamond (C): Pure substance - Element

7. Salt (NaCl): Pure substance - Compound

8. Air: Mixture - Homogeneous

9. Helium gas: Pure substance - Element

10. Carbon dioxide gas: Pure substance - Compound

11. Coffee: Mixture - Homogeneous

12. Caffeine (C8H10N4O2): Pure substance - Compound

13. Tomato soup: Mixture - Homogeneous

14. Chicken noodle soup: Mixture - Heterogeneous

15. Brass: Mixture - Homogeneous

16. Pure water: Pure substance - Compound

17. Pure iron: Pure substance - Element

18. Sweat: Mixture - Homogeneous

19. Baking soda (NaHCO3): Pure substance - Compound

The answer is C. 2 m/s

Answer: 2m/s

Explanation:

Initial position = 2m

Final position = 10m

Distance = 10-2 = 8m

Time = 4s

Velocity = distance(m) /time(s)

Velocity = 8/4 = 2m/s

Answer. By adding the proportionality constant .

Explanation:

suppose 'x' a  is directly proportional to the 'y' , where x and y are variables:

x ∝ y

with an input of constant value 'K' proportionality relation gets converted into  an equation:

x = K y

For example : Gravitational force is directly proportional to the product of two masses and inversely proportional to the square of the distance between the two masses.

F ∝ [tex]\frac {m_1m_2}{r^{2}}[/tex]

To convert this proportionality relation constant 'G'  was introduced known as gravitational constant whose value remains constant under every conditions.

[tex]F=\frac {G\times m_1m_2}{r^{2}}[/tex]

[tex]G=6.67408\times 10^{-11}m^3Kg^{-1}s^{-2}[/tex]

The correct answer is: by the transfer of one or more electrons from one atom to another.

Final answer:

A suspension is a heterogeneous mixture where the dispersed particles are large enough to settle upon standing. Mud in water is an example of a suspension because it has large particles that are visible, the mixture is cloudy, and particles settle when undisturbed.

Explanation:

To identify which mixture is classified as a suspension, it's essential to understand the particle sizes involved in different mixtures. A suspension contains particles with diameters around 1 µm (1000 nm) that are dispersed throughout another phase. Examples of suspensions include muddy water and paint. In contrast, colloids involve much smaller particles (2 to about 500 nm in diameter) that do not settle on standing, such as milk or fog.

Considering the information provided, a suspension is a heterogeneous mixture where the dispersed particles are large enough to settle out upon standing. These particles can often be separated from the dispersing medium by filtration. In contrast, a solution has much smaller particles that do not settle and cannot be filtered out.

From the examples provided, mud in water fits the definition of a suspension. The particles are of appropriate size, it's heterogeneous, the mixture is cloudy due to the particles, and it will allow for settling over time if left undisturbed.

Answer:- 12.7%

Solution:- It says, ammonium phosphate is 60.9%. It means if we assume 100 g of the sample then there is 60.9 g ammonium phosphate in it.

Formula of ammonium phosphate is [tex](NH_4)_3PO4[/tex] and it's molecular weight is 149 grams per mol. There is only one P in the formula and so the mass of P in 149 g of ammonium phosphate is 31 g(atomic mass of P).

Now, we could use the proportions to find out the mass percentage of P in the sample.

31 g P is present in 149 g of ammonium phosphate, how many grams of P would be present in 60.9 g of ammonium phosphate. Let's set the proportions as:

[tex]\frac{31}{149}=\frac{x}{60.9}[/tex]

[tex]x=\frac{31(60.9)}{149}[/tex]

[tex]x=12.7[/tex]

This 12.7 g of phosphorous is present in 100 g of the sample means there is 12.7% phosphorous in the sample.

Answer:

all of these        

Answer:

all of these    

Explanation:

The answer to problem is [He] 2s1. Hope it helps

Your answer is [He] 2s1

Hope that helps :)