All categories

2 years ago

I need to know the answers

Chemistry

1 answer:

suter [353]2 years ago

3 0

If you notice in the graph for antibiotic A, the number of bacteria actually INCREASES as time increases after the antibiotic was given. In the second graph, the amount of bacteria increases just a little bit (likely as the antibiotic sets in) and then decreases until no bacteria is left at all. This means that the antibiotic was the most successful because not only did the amount of bacteria decrease over time, but also all of the bacteria were eventually killed.

The last graph is shown as no antibiotic given. This is a graph showing the control group. There is always a control group in an experiment where nothing is done to the group. This is used to compare the results in the end of the experiment.

You might be interested in

6 C(s) + 3 H2(g) → 2 C6H6(l) Δ H = 49 kJ<br><br> TRUE or FALSE

VMariaS [17]

Answer:

True => ΔH°f for C₆H₆ = 49 Kj/mole

Explanation:

See Thermodynamic Properties Table in appendix of most college level general chemistry texts. The values shown are for the standard heat of formation of substances at 25°C. The Standard Heat of Formation of a substance - by definition - is the amount of heat energy gained or lost on formation of the substance from its basic elements in their standard state. C₆H₆(l) is formed from Carbon and Hydrogen in their basic standard states. All elements in their basic standard states have ΔH°f values equal to zero Kj/mole.

7 0

3 years ago

The activation energy of a reaction is 56.9 kj/mol and the frequency factor is 1.5×1011/s. Part a calculate the rate constant of

Vanyuwa [196]

We will use Arrehenius equation

lnK = lnA -( Ea / RT)

R = gas constant = 8.314 J / mol K

T = temperature = 25 C = 298 K

A = frequency factor

ln A = ln (1.5×10 ^11) = 25.73

Ea = activation energy = 56.9 kj/mol = 56900 J / mol

lnK = 25.73 - (56900 / 8.314 X 298) = 2.76

Taking antilog

K = 15.8

5 0

3 years ago

A student environmental group is creating a campaign for locally sourced energy resources.

Cloud [144]

Answer: The correct option is B. A farmer with a field of solar panels

Explanation: Since the question says that the students are related to environmental group so they must run a campaign for the renewable energy resources and avoid the use of natural non renewable resources. coal, gas and many others like these are non renewable sources of energy. A farmer using solar panels in his field must be appreciated because he is using an environment friendly source of energy.

8 0

3 years ago

Read 2 more answers

An element has an average atomic mass of 1.008 amu. It consists of two isotopes , one having a mass of 1.007 amu, and one having

dimulka [17.4K]

Answer:

The most abundant isotope is 1.007 amu.

Explanation:

Given data:

Average atomic mass = 1.008 amu

Mass of first isotope = 1.007 amu

Mass of 2nd isotope = 2.014 amu

Most abundant isotope = ?

Solution:

First of all we will set the fraction for both isotopes

X for the isotopes having mass 2.014 amu

1-x for isotopes having mass 1.007 amu

The average atomic mass is 1.008 amu

we will use the following equation,

2.014x + 1.007 (1-x) = 1.008

2.014x + 1.007 - 1.007 x = 1.008

2.014x - 1.007x = 1.008 - 1.007

1.007 x = 0.001

x= 0.001/ 1.007

x= 0.0009

0.0009 × 100 = 0.09 %

0.09 % is abundance of isotope having mass 2.014 amu because we solve the fraction x.

now we will calculate the abundance of second isotope.

(1-x)

1-0.0009 = 0.9991

0.9991 × 100= 99.91%

6 0

3 years ago

Determine the percent ionization of a 0.225 M solution of benzoic acid. Express your answer using two significant figures.

Assoli18 [71]

Answer:

1.68% is ionized

Explanation:

The Ka of benzoic acid, C₇H₆O₂, is 6.46x10⁻⁵, the equilibrium in water of this acid is:

C₇H₆O₂(aq) + H₂O(l) ⇄ C₇H₅O₂⁻(aq) + H₃O⁺(aq)

Ka = 6.46x10⁻⁵ = [C₇H₅O₂⁻] [H₃O⁺] / [C₇H₆O₂]

<em>Where [] are concentrations in equilibrium</em>

In equilibrium, some 0.225M of the acid will react producing both C₇H₅O₂⁻ and H₃O⁺, the equilibrium concentrations are:

[C₇H₆O₂] = 0.225-X

[C₇H₅O₂⁻] = X

[H₃O⁺] = X

Replacing:

6.46x10⁻⁵ = [X] [X] / [0.225-X]

1.4535x10⁻⁵ - 6.46x10⁻⁵X = X²

1.4535x10⁻⁵ - 6.46x10⁻⁵X - X² = 0

Solving for X:

X = -0.0038. False solution, there is no negative concentrations.

X = 0.00378M. Right solution.

That means percent ionization (100 times Amount of benzoic acid ionized over the initial concentration of the acid) is:

0.00378M / 0.225M * 100 =

<h3>1.68% is ionized</h3>

8 0

2 years ago