Rate or Reaction Past Exam Questions 2
10 Fatimah investigates the reaction between sodium hydrogencar
acid.
reaction between sodium hydrogencarbonate and dilute hydrocrc
She always adds 0.5g of sodium hydrogencarbonate to 20 cm of dilute hydrochia
She measures the time it takes for the reaction mixture to stop bubbling.
This is called the reaction time.
She does five different experiments.
She keeps the temperature the same.
Each experiment uses a different concentration of acid.
Look at a graph of her results.
1004
60F
reaction time
in seconds
0.5
1.5
2
.0
2.5
1.0
concentration in mol/dms
Fatimah concludes that as the concentration of acid increases, the rate of reaction increases.
Explain, with a reason, whether the results support Fatimah's conclusion.
Use the reacting particle model to explain Fatimah's results.
The quality of written communication will be assessed in your answer to this question.

The part of the engineering process that she is most likely engaged in is identifying a need. Thus, the correct option is D.

Skin cancer may be defined as the circumstance in which there is an uncontrolled growth of abnormal skin cells occur. It causes severe damage to the skin.

After observing the mortality data of last year, scientists identified a need to overcome the threat of a situation that causes a higher number of deaths last year.

Therefore, the correct option for this question is D.

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Final answer:

The scientist noticing an increase in skin cancer deaths is engaged in Identifying a need, the first step of the engineering process where problems are recognized.

Explanation:

If a scientist has noticed a significant increase in the number of deaths related to skin cancer from the previous year, she is most likely engaged in Identifying a need (Option D). This is the first step in the engineering process, where a problem or opportunity is recognized that may need a new or modified technological solution. In the context of this scenario, the identification of the increased skin cancer deaths could lead to a need for improved public health policies, educational programs on sun safety, or the development of better skin protection products.

Answer:

Organic

Explanation:

Glucose is an organic compound, as its structure contains atoms of carbon, which are the main constituents of organic molecules. Glucose is specifically a monosaccharide that belongs to the group of carbohydrates, one of the four types of organic molecules.

C6H12O6 is an organic compound because it contains carbon in its structure.

Organic compounds are carbon-based molecules, essential to life and diverse in structure. They include hydrocarbons like methane, functional groups like alcohols, and complex biomolecules such as proteins and DNA. Organic chemistry studies their synthesis, structure, and properties, playing a crucial role in pharmaceuticals, agriculture, and materials science

In the given case C6H12O6 is an organic compound as organic compounds are defined as covalently bonded compounds containing carbon, excluding carbonates and oxides. C6H12O6 is composed of carbon (C), hydrogen (H), and oxygen (O) atoms, making it an organic compound.

Answer:

14.3 g SO₃

Explanation:

2S + 3O₂ → 2SO₃

First, find the limiting reactant.  To do that, calculate the mass of oxygen needed to react with all the sulfur.

5.71 g S × (1 mol S / 32 g S) = 0.178 mol S

0.178 mol S × (3 mol O₂ / 2 mol S) = 0.268 mol O₂

0.268 mol O₂ × (32 g O₂ / mol O₂) = 8.57 g O₂

There are 10.0 g of O₂, so there's enough oxygen.  The limiting reactant is therefore sulfur.

Use the mass of sulfur to calculate the mass of sulfur trioxide.

5.71 g S × (1 mol S / 32 g S) = 0.178 mol S

0.178 mol S × (2 mol SO₃ / 2 mol S) = 0.178 mol SO₃

0.178 mol SO₃ × (80 g SO₃ / mol SO₃) = 14.3 g SO₃

Answer:

Stannic fluoride, SnF4

Explanation:

The chemical formula of Barium nitride is Ba(NO3)2.

The chemical formula of Cobaltous chloride is COCl2.

The chemical formula of Sodium Oxide is Na2O.

So the correct one is stannic fluoride, SnF4.

Answer:

The name and formula is paired correctly for Stannic Fluoride - [tex]SnF_4[/tex]

Explanation:

In this case, we have four names of chemical substances and four formulas. So, we should check each one of those in order to be sure if the name and the formula are paired correctly.

First: Sodium Oxide. The formula for this oxide is [tex]Na_2O[/tex]. The formula paired is NaO. In this case, formula and name are not correctly paired. NaO is not a chemical substance, due to the fact that Oxygen always should have -2 of valence as it was shown in the right formula [tex]Na_2O[/tex]

Second: Cobaltous Chloride. The formula for this Chloride is [tex]CoCl_2[/tex]. The formula paired is [tex]CoCl_3[/tex].

[tex]CoCl_3[/tex] name is Cobaltic Chloride. Taking into account both formula we can mention that formula and name are not correctly paired.

Third: Barium Nitride. The formula for this Nitride is [tex]Ba_3N_2[/tex]. The formula paired is BaN. Formula and name are not correctly paired. BaN is not a chemical substance, Valence of elements are not coherent with the groups in the periodic table.

Finally: Stannic Fluoride. The formula for this Fluoride is [tex]SnF_4[/tex]. The formula paired is [tex]SnF_4[/tex]. So, this is the formula and name correctly paired.  

Answer:

1+2i

Explanation:

Answer:

1+2i

Explanation:

Let the two complex numbers in the question to be as shown below,

a + bi = 4 − 3i and s + ti = -2 + 7i.

Apply the Midpoint Formula for the 2 complex numbers which are a + bi and s + ti is:

[tex]Midpoint=\frac {a+s}{2}+ \frac {b+t}{2}i[/tex]

Applying values as:

[tex]Midpoint=\frac {4-2}{2}+ \frac {-3+7}{2}i[/tex]

Hence, the midpoint is 1+2i

Answer:

Both fission and fusion are nuclear reactions that produce energy, but the applications are not the same. Fission is the splitting of a heavy, unstable nucleus into two lighter nuclei, and fusion is the process where two light nuclei combine together releasing vast amounts of energy.

Explanation:

Final answer:

Nuclear fission is used primarily in nuclear reactors to generate electricity and in nuclear weapons. While it is more environmentally friendly than fossil fuels, it still produces radioactive waste, challenging the perception of it as a zero-waste energy source.

Explanation:

Applications of Fission Reactions

Nuclear fission reactions involve the splitting of a heavy atomic nucleus into two or more lighter nuclei, along with the release of energy and neutrons. This process is not only fundamental in nuclear power plants, where the energy released is harnessed to generate electricity, but also underlies the destructive power of nuclear weapons.

Nuclear reactors use controlled fission reactions to heat water, producing steam that drives turbines to generate electricity. This method of producing power is seen as a more environmentally friendly alternative to fossil fuels, as it does not produce greenhouse gases. Moreover, many countries see the development and application of nuclear technology as critical for ensuring energy security.

However, it is important to note that while nuclear power is seen as a potential solution to global warming, it is not a zero-waste energy source. The spent nuclear fuel and other radioactive waste generated by nuclear reactors pose significant disposal challenges.

Answer:

Among the three major types of rock, fossils are most commonly found in sedimentary rock. Unlike most igneous and metamorphic rocks, sedimentary rocks form at temperatures and pressures that do not destroy fossil remnants. Often these fossils may only be visible under magnification.

Explanation:

Answer:

n = 9

Explanation:

Given parameters:

Molar mass of Na₂SO₄.nH₂O = 304.04gmol⁻¹

Solution

To find the hydration number n, we simply express atomic masses of the atoms in the compound as equal to the given molar mass.

Atomic mass of Na = 23g

                           S = 32g

                           O = 16g

                            H = 1g

       Molar mass of the compound is evaluated as:

       2(23) + 32 + 4(16) + n[2(1) + 16] = 304.04

       46 + 32 + 64 + 18n = 304.04

          142 + 18n = 304.04

              18n = 304.04 - 142

              18n = 162.04

                n = 9

Answer:

Dr. Patel, a cardiologist, presents her findings on heart disease

Explanation:

Answer: 0.4

Explanation: The easiest way to do this is to get a denominator of 10. To do this, multiply each number in 2/5 by 2. You will get the fraction 4/10. With the denominator of 10, the answer would be 0.4 by putting the decimal in front of the number.

Answer:

D) forms hydronium ions in water

Explanation:

Texture and conductivity are physical properties which makes answer A and B wrong. Answer C does not refer to a chemical reaction.

Answer:

Weathering is the breakdown of rocks into smaller particles called sediment (not sediments)

Mechanical weathering is when rocks are physically broken into smaller pieces, but the minerals in the rock remain the same

When a rock is broken down in a way that changes the mineral composition, it is called Chemical Weathering.

The blanks about Weathering in the question are filled as follows;

According to the question;

For Statement 1:

For Statement 2;

For Statement 3:

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Answer: The benzoic acid is a weak acid.

Explanation:

According to the Bronsted-Lowry conjugate acid-base theory:

The chemical equation for the reaction of potassium benzoate with water follows:

[tex]C_6H_5COOK+H_2O\rightarrow C_6H_5COOH+KOH[/tex]

Here, benzoate anion is accepting a proton from water and is acting as conjugate base. Water is acting as conjugate acid.

The solution formed is basic solution because of the formation of potassium hydroxide.

When a strong base and weak acid reacts, it leads to the formation of basic solution.

Hence, the benzoic acid is a weak acid.

A conjugate base differs from the forming acid in that it has one additional negative charge and one fewer H atom. It is a material that remains after an acid loses its hydrogen ion. Here benzoic acid is a weak acid. The correct option is C.

Benzoic acid is a weak acid because it is an organic acid. The acid is more potent at higher proton-leaving rates. Because of its resonance structure, benzoic acid has a reduced ability to leave protons, which restricts its proton-leaving potential.

The chemical equation for the reaction of potassium benzoate with water follows:

C₆H₅COOK + H₂O → C₆H₅COOH + KOH

Here, the benzoate anion is accepting a proton from water and is acting as a conjugate base. Water is acting as conjugate acid. When a strong base and weak acid react, it leads to the formation of a basic solution.

Thus the correct option is C.

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Answer:

nobel gass are found atmosphere

Answer:

Noble gases are found as monatomic molecules is a TRUE statement.

Explanation:

Noble gases are monoatomic elements. That is they exist as a single atom in nature.

Noble gases are the only elements which are stable at room temperature and pressure.

Except helium which has 2 valence electrons all other elements have 8 valence electrons (electrons in the outer shell) This is the reason why the noble gases are non reactive that is they are inert in nature.

It is difficult to oxidize or reduce noble gases and hence they form very few compounds.

Answer:

oxidation

Explanation:

oxidation number are based on the distribution of electrons in a molecule

Answer:

Explanation:

Since the equation is not given, let us write and balance it:

  Reactants: Carbon dioxide (CO₂)

                      Water(H₂O)

 Products: Glucose(C₆H₁₂O₆)

                   Oxygen(O₂)

The reaction equation is shown below:

                  CO₂ + H₂O → C₆H₁₂O₆ + O₂

But the equation is not balanced:

    to balance the equation

          aCO₂ + bH₂O → cC₆H₁₂O₆ + dO₂

  for C:

         a = 6c, if c = 1 then a = 6

  for O:

        2a + b = 6c + 2d

  for H:

       2b = 12c, since c = 1, b = 6

In 2a + b = 6c + 2d, solving for d:

   2(6) + 6 = 6(1) + 2d

      18 = 6 + 2d

         d = 6

Therefore, the balanced equation is:

                       6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂

Photosynthesis is the process where six molecules of carbon dioxide and six molecules of water combine, using light energy, to produce one molecule of glucose and six molecules of oxygen. This procedure is unique to plant cells and fosters life as we know it on Earth.

The process you're referring to is indeed called photosynthesis and this process happens in cells of plants, which absorb sunlight to carry out this operation. The balanced equation for photosynthesis is written as:

6CO₂ + 6H₂O -------light------> C₆H₁₂O₆ + 6O₂

In other words, this equation reads: Six molecules of carbon dioxide plus six molecules of water, using light energy, produce one molecule of glucose and six molecules of oxygen. This procedure, which can only be completed by plant cells, enhances life on Earth as we know it.

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Answer:

=C₄H₄O₂

Explanation:

Given the empirical formula of a molecule, the he the quotient of the molecular mas and and the empirical mass=constant.

84.0 g/mol/mass of(C₂H₂O)=constant

=84/(12×2+1×2×16)

=84/42

=2

Therefore, the molecular formula is (C₂H₂O)₂=C₄H₄O₂

Answer:

[tex]C_2 H_2 O \times 2=C_4 H_4 O_2[/tex] is the molecular formula

Explanation:

Empirical formula is the simplest form of a Molecular formula.

For example  

Molecular formula of glucose is [tex]C_6 H_{12} O_6[/tex]

Its empirical formula is [tex]C_1 H_2 O_1[/tex]

The subscript numbers of the molecular formula is divided by a common number n=6 here.

Another example:

Molecular formula of Octane is [tex]C_8 H_{18}[/tex] and Its empirical formula will be [tex]C_4 H_9[/tex]  

Subscripts divided by n=2.

To find n we make use of the formula  

[tex]\frac {(molecular mass )}{(empirical formula mass)}=n[/tex]

[tex]= \frac {84.0g}{(C_2H_2O mass)}\\\\=\frac {84.0g}{(24+2+16)g}=\frac {84.0g}{42g}=2[/tex]

So, we see n=2 here

Empirical formula × n = molecular formula

[tex]C_2 H_2 O \times 2=C_4 H_4 O_2[/tex] is the molecular formula

(Answer)

Please note:

Molar mass is the mass of 1 mole of the substance and its unit is g/mol .

n is the number of moles by which the empirical formula is multiplied to get the molecular formula of the compound.

Answer:

0.22 atm

Explanation:

The total pressure is the sum of the partial pressures.

P = P₁ + P₂ + P₃

1.25 atm = 0.68 atm + 0.35 atm + P

P = 0.22 atm

Answer:

0.22 atm

Explanation:

First, you need to add up each of the values of the known gases

0.68+0.35

Then you need to subtract that value from the total pressure to find the partial pressure of the third value

1.25-(0.68+0.35)

By doing that you get the answer of 0.22 atm

Answer:

C,D

Explanation:

Answer:

C D

Explanation:

Explanation:

First conversion factor: moles of SO₄ per mole of Al₂(SO₄)₃.

3 mol SO₄ / mol Al₂(SO₄)₃

Second conversion factor: moles of S per mole of SO₄.

1 mol S / mol SO₄

Altogether:

(3 mol SO₄ / mol Al₂(SO₄)₃) × (1 mol S / mol SO₄) = 3 mol S / mol Al₂(SO₄)₃

To relate moles of S to moles of Al2(SO4)3, we use the compound's 2:3 ratio to establish that 1 mole of Al2(SO4)3 has 3 moles of S. Conversion factors are 1 mole Al2(SO4)3/3 moles S and 3 moles S/1 mole Al2(SO4)3. These allow for conversions between the moles of the two substances.

To construct a pair of conversion factors that relate moles of S to moles of Al2(SO4)3, we need to look at the chemical compound's formula. The compound aluminum sulfate, Al2(SO4)3, shows there are three sulfate (SO42-) ions for every two aluminum (Al3+) ions.

This indicates a 2:3 ratio between Al and SO4 in the compound. Each sulfate ion contains one atom of sulfur (S), so for every mole of Al2(SO4)3, there are three moles of sulfur atoms (S). Thereby, the conversion factors are:

These factors can be used to convert moles of sulfur to moles of aluminum sulfate and vice versa.

Answer:

D) constructive

Explanation:

Deposition is a constructive force since it involves dumping sediment in a particular location.

Constructive is the correct answer. A deposition is a constructive force when it involves dumping into sediment a particular location. I hope this will help you. Have a wonderful day!

Answer:

A double covalent bond.

Explanation:

A double covalent bond forms between two oxygen atoms.

A double covalent bond is when two pairs of electrons are shared between the atom. Usually, there is only one pair, rather than two pairs.

The electrostatic attractive interaction between the same or different elements is called bonds. A nonpolar covalent is formed between two oxygen atoms. Thus, option a is correct.

A chemical bond that involves the mutual sharing of electrons between the outer valence shell of the elemental atom is called a covalent bond. The covalent bonds are of two types namely polar and non-polar.

The polar covalent bond is the unequal sharing of the electrons in the outer shell due to differences in electronegativities. The non-polar covalent bond is formed between the same or different elements in a compound.

In a non-polar covalent bond like two oxygen atoms, the valence electrons are shared equally and have negligible electronegativity differences.

Therefore, option a. two oxygen atoms form a nonpolar covalent.

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Answer:

42.5 g

Explanation:

Calculate the mass of the soft drink given the density and volume:

355 mL × 1.04 g/mL = 369.2 g

Now calculate the mass of sucrose given the percentage:

0.115 × 369.2 g = 42.46 g

Rounded to 3 significant figures, the mass is 42.5 g.

Answer:

42.458 g of sucrose is contained in 355 mL (12 oz) of the soft drink

Explanation:

Volume of the soft drink = 355mL

Density = 1.04 g/mL

We know

Density = Mass / Volume

Rearranging the formula  

Mass of soft drink = Density × volume

[tex]=1.04 g/mL \times 355mL=369.2 g[/tex]

[tex]Mass = \frac {(mass of solute)}{(mass of solution )} \times 100%[/tex]

[tex]11.5  = \frac {(mass of solute (sucrose))}{(mass of solution(soft drink) )} \times 100%[/tex]

[tex]11.5  = \frac {(mass of solute (sucrose))}{(369.2 g)} \times 100%[/tex]

So

Mass of sucrose

[tex]=\frac {(11.5 \times 369.2g)}{(100)}[/tex]

= 42.458 g  is the Answer

Answer:

From n=1 to n=2

Explanation:

Electrons in n=1 are strongly attracted to the nucleus and therefore will require great force to overcome the electrostatic force of attraction to displace them from the energy level to another.

The electrostatic force reduces as you progress to the outer energy levels.

Answer:

C. from n = 1 to n = 2

Explanation:

A.

[tex]\Delta E=E_{final}-E_{initial}[/tex]

[tex]\Delta E=-1312[\frac{1}{(n_f^2 )}-\frac {1}{(n_i^2 )}]KJ mol^{-1}[/tex]

[tex]\Delta E=-1312[\frac{1}{(4^2 )}-\frac {1}{(3^2 )}]KJ mol^{-1}[/tex]

[tex]\Delta E=-1312[\frac{1}{(16 )}-\frac {1}{(9)}]KJ mol^{-1}[/tex]

[tex]\Delta E=-1312[0.0625-0.111]KJ mol^{-1}[/tex]

[tex]\Delta E=64 KJ mol^{-1}[/tex]

B.

[tex]\Delta E=E_{final}-E_{initial}[/tex]

[tex]\Delta E=-1312[\frac{1}{(n_f^2 )}-\frac {1}{(n_i^2 )}]KJ mol^{-1}[/tex]

[tex]\Delta E=-1312[\frac{1}{(3^2 )}-\frac {1}{(2^2 )}]KJ mol^{-1}[/tex]

[tex]\Delta E=-1312[\frac{1}{(9 )}-\frac {1}{(4)}]KJ mol^{-1}[/tex]

[tex]\Delta E=-1312[0.111-0.25]KJ mol^{-1}[/tex]

[tex]\Delta E=182 KJ mol^{-1}[/tex]

C.

[tex]\Delta E=E_{final}-E_{initial}[/tex]

[tex]\Delta E=-1312[\frac{1}{(n_f^2 )}-\frac {1}{(n_i^2 )}]KJ mol^{-1}[/tex]

[tex]\Delta E=-1312[\frac{1}{(2^2 )}-\frac {1}{(1^2 )}]KJ mol^{-1}[/tex]

[tex]\Delta E=-1312[\frac{1}{(4)}-\frac {1}{(1)}]KJ mol^{-1}[/tex]

[tex]\Delta E=-1312[0.25-1]KJ mol^{-1}[/tex]

[tex]\Delta E=984 KJ mol^{-1}[/tex]

Answer:

Water

Explanation:

Water molecules are known to have a melting point of 0°C and a boiling point of 100°C.

The melting and boiling points are as a result of the intermolecular force of attraction between the molecules of water. The predominant bond type that dictates the property of the melting and boiling point is the hydrogen bonding. This bond is a strong force of attraction and it impacts on the physical properties of water.

Answer:

Water

Explanation:

The substance that has a melting point at 0 and a boiling point at 100 is water.  Water is the only substance that fits into this category.  According to van.physics.illinois.edu, it states the following "For pure water, the boiling point is 100 degrees Celsius (212 Fahrenheit) at one atmosphere of pressure, and the melting point is 0 degrees Celsius (32 degrees Fahrenheit) at one atmosphere of pressure."

Answer:  Water

D

Temperature is equivalent to kinetic energy under the collision theory of matter. This shows that losing kinetic energy to the air (a "transfer" of thermal energy) is the same as a decreasing temperature.

Answer:

D

Explanation:

Answer:

1-3 2-2 3-1

Explanation:

The answer is answer choice 3

Answer:

(C) 503 g

Explanation:

Balanced reaction:

2NH₃ + 2O₂ → N₂O + 3H₂O

Stoichiometry:

317 g NH₃ × (1 mol NH₃ / 17.03 g NH₃) = 18.61 mol NH₃

18.61 mol NH₃ × (3 mol H₂O / 2 mol NH₃) = 27.92 mol H₂O

27.92 mol H₂O × (18.02 g H₂O / mol H₂O) = 503 g H₂O

Answer:

(C) 503 g of water, H2O, are produced from 317 grams of ammonia and excess oxygen

Explanation:

[tex]2 NH_3+2 O_2>N_2 O+3 H_2 O[/tex]

Molar mass of

[tex]H_2 O=(2\times1.008)+15.999=18.02 g/mol[/tex]

Molar mass of

[tex]NH_3=14.01+(3\times1.008)=17.03 g/mol[/tex]

The conversions are

Step 1:

Mass [tex]NH_3[/tex] to moles [tex]NH_3[/tex] by dividing with molar mass [tex]NH_3[/tex]

Step 2:

Moles [tex]NH_3[/tex] to moles [tex]H_2 O[/tex] by using mole ratio of [tex]NH_3:H_2 O[/tex] i.e., 2 : 3

Step 3:

Moles [tex]H_2 O[/tex] to mass [tex]H_2 O[/tex] by multiplying with molar mass [tex]H_2 O[/tex]

[tex]317gNH_3  \times \frac {(1mol NH_3)}{(17.03gNH_3 )} \times \frac {(3mol H_2 O)}{(2mol NH_3 )} \times \frac {(18.02g H_2 O)}{(1mol H_2 O)}[/tex]

[tex]= 503g H_2 O[/tex] is formed.

(Answer)

Please note :

To convert moles to mass, we multiply by molar mass  

To convert mass to moles, we divide by molar mass

Molar mass is the mass of 1 mole of the substance

For example molar mass of [tex]CO_2[/tex] is

[tex](12.0+2\times16)=44 g/mol[/tex]

(we just add the atomic mass of the atoms to get the molar mass of the substance).