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4 years ago

Two major discoveries of the gold foil experiment

1 answer:

5 0

Rutherford's gold foil experiment proved that there was a small, dense, positively charged nucleus at the center, which contained most of the mass of the atom. Which contained electrons orbiting the nucleus.

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Acetylsalicylic acid (aspirin), HC9H7O4, is the most widely used pain reliever and fever reducer. Find the pH of 0.035 M aqueous

KatRina [158]

The pH of 0.035 M aqueous aspirin is 2.48

Explanation:

We are given:

Concentration of aspirin = 0.035 M

The chemical equation for the dissociation of aspirin (acetylsalicylic acid) follows:

$HC_9H_7O_4\rightleftharpoons H^++C_9H_7O_4^-$

Initial: 0.035

At eqllm: 0.035-x x x

The expression of $K_a$ for above equation follows:

$K_a=\frac{[C_9H_7O_4^-][H^+]}{[HC_9H_7O_4]}$

We are given:

$K_a=3.6\times 10^{-4}$

Putting values in above expression, we get:

$3.6\times 10^{-4}=\frac{x\times x}{(0.035-x)}\\\\x=-0.0037,0.0033$

Neglecting the value of x = -0.0037 because concentration cannot be negative

So, concentration of $H^+$ = x = 0.0033 M

To calculate the pH of the solution, we use the equation:

$pH=-\log[H^+]$

We are given:

$H^+$ = 0.0033 M

Putting values in above equation, we get:

$pH=-\log(0.0033)\\\\pH=2.48$

Hence, the pH of 0.035 M aqueous aspirin is 2.48

7 0

3 years ago

A mystery object has a density of .75; will it sink or float?

brilliants [131]

Answer:float

Explanation:

8 0

3 years ago

Which of the following statements about cytokines is FALSE? Which of the following statements about cytokines is FALSE? They are

gizmo_the_mogwai [7]

Answer:

There are 10 types

Explanation:

Cytokines are the molecules produced by the immune cells involved in the immune response like the B cells, T cells, macrophages and other cells.

They are produced as a means of communication between the immune cells which could act as a signalling molecule. The chemical nature of these cytokines is that they are either the proteins or the glycoproteins.

There are many types of cytokine produced in response to antigens which could be interleukin, interferon which could play a different role. These cytokines are present in more than 10 types of forms therefore the selected option is correct.

6 0

3 years ago

A chemical reaction takes place in which energy is released. Arrange the reaction’s characteristics in order from start to finis

Aliun [14]

Endothermic reactions, on the other hand, absorb heat and/or light from their surroundings. For example, decomposition reactions are usually endothermic. In endothermic reactions, the products have more enthalpy than the reactants. Thus, an endothermic reaction is said to have a positive enthalpy of reaction. This means that the energy required to break the bonds in the reactants is more than the energy released when new bonds form in the products; in other words, the reaction requires energy to proceed

5 0

3 years ago

Given: 36.7 grams of CaF2 is added to 300 mL water. Find molarity?

BigorU [14]

<h3>Answer:</h3>

2 M

<h3>General Formulas and Concepts:</h3>

Math

Pre-Algebra

Order of Operations: BPEMDAS

Brackets
Parenthesis
Exponents
Multiplication
Division
Addition
Subtraction

Left to Right

Chemistry

Unit 0

Reading a Periodic Table
Using Dimensional Analysis

Aqueous Solutions

Molarity = moles of solute / liters of solution

<h3>Explanation:</h3>

Step 1: Define

36.7 g CaF₂

300 mL H₂O

Step 2: Identify Conversions

Molar Mass of Ca - 40.08 g/mol

Molar Mass of F - 19.00 g/mol

Molar Mass of CaF₂ - 40.08 + 2(19.00) = 78.08 g/mol

1000 mL = 1 L

Step 3: Convert

Solute

Set up: $\displaystyle 36.7 \ g \ CaF_2(\frac{1 \ mol \ CaF_2}{78.08 \ g \ CaF_2})$
Multiply: $\displaystyle 0.470031 \ mol \ CaF_2$

Solution

Set up: $\displaystyle 300 \ mL \ H_2O(\frac{1 \ L \ H_2O}{1000 \ mL \ H_2O})$
Multiply: $\displaystyle 0.3 \ L \ H_2O$

Step 4: Find Molarity

Substitute [M]: $\displaystyle x \ M = \frac{0.470031 \ mol \ CaF_2}{.3 \ L \ H_2O}$
Divide: $\displaystyle x = 1.56677 \ M$

Step 5: Check

Follow sig fig rules and round. We are given 1 sig fig as our lowest.

1.56677 M ≈ 2 M

8 0

3 years ago