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3 years ago

What do scientist use to form a hypothesis

Chemistry

2 answers:

likoan [24]3 years ago

8 0

Answer:

an if/then statement

Explanation:

Kazeer [188]3 years ago

7 0

A hypothesis is usually written in the form of an if/then statement.

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How many grams of pure naoh must be used to prepare 10.0 l of a solution that has a ph of 13? __________g?

padilas [110]

40 g NaOH. You must use 40 g NaOH to prepare 10.0 L of a solution that has a pH of 13.

Step 1. Calculate the pOH of the solution

pOH = 14.00 – pH = 14.00 -13 = 1

Step 2. Calculate the concentration of NaOH

[NaOH] = [OH^(-)] = 10^(-pOH) mol/L = 10^(-1) mol/L = 0.1 mol/L

Step 3. Calculate the moles of NaOH

Moles of NaOH = 10.0 L solution × (0.1 mol NaOH/1 L solution) = 1 mol NaOH

Step 4. Calculate the mass of NaOH

Mass of NaOH = 1 mol NaOH × (40.00 g NaOH/1 mol NaOH) = 40 g NaOH

8 0

3 years ago

How many C-13 atoms are present, on average, in a 1.6000×104-atom sample of carbon?

san4es73 [151]

I don't know why I am answering this question but assuming C-13 has a natural abundance of 1.07%:

(1.6000x10^4)(0.0107) = 171.2 = 171 atoms of C-13

5 0

3 years ago

Read 2 more answers

What most accurately explains whether liquid water or ice has a higher density, and why?

nata0808 [166]

Answer:

I think your answer is either b or c but I think b is more likely to be your answer

7 0

3 years ago

ou will prepare 250-mL of this solution using a 30% (m/v) NaOH stock solution. How many mL of the NaOH stock solution will you n

ArbitrLikvidat [17]

Answer:

$\boxed{\text{3.3 mL}}$

Explanation:

You must convert 30 % (m/v) to a molar concentration.

Assume 1 L of solution.

1. Mass of NaOH

$\text{Mass of NaOH} = \text{1000 mL solution } \times \dfrac{\text{30 g NaOH}}{\text{100 mL solution}} = \text{300 g NaOH}$

2. Moles of NaOH

$\text{Moles of NaOH} = \text{300 g NaOH} \times \dfrac{\text{1 mol NaOH}}{\text{40.00 g NaOH}} = \text{7.50 mol NaOH}$

3. Molar concentration of NaOH

$c= \dfrac{\text{moles}}{\text{litres}} = \dfrac{\text{7.50 mol}}{\text{1 L}} = \text{7.50 mol/L}$

4. Volume of NaOH

Now that you know the concentration, you can use the dilution formula .

$c_{1}V_{1} = c_{2}V_{2}$

to calculate the volume of stock solution.

Data:

c₁ = 7.50 mol·L⁻¹; V₁ = ?

c₂ = 0.1 mol·L⁻¹; V₂ = 250 mL

Calculations:

(a) Convert millilitres to litres

$V = \text{250 mL} \times \dfrac{ \text{1 L}}{\text{1000 mL}} = \text{0.250 L}$

(b) Calculate the volume of dilute solution

$\begin{array}{rcl}7.50V_{1} & = & 0.1 \times 0.250\\7.50V_{1} &= & 0.0250\\V_{1} & = & \text{0.0033 L}\\& = & \textbf{3.3 mL}\\\end{array}$

$\text{You will need $\boxed{\textbf{3.3 mL}}$ of the stock solution.}$

4 0

3 years ago

Calculate the number of Li atoms in 7.8 mol of Li.

Gwar [14]

<h3>Answer:</h3>

4.7 × 10²⁴ atoms Li

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

Math

Pre-Algebra

Order of Operations: BPEMDAS

Brackets
Parenthesis
Exponents
Multiplication
Division
Addition
Subtraction

Left to Right

Chemistry

Atomic Structure

Avogadro's Number - 6.022 × 10²³ atoms, molecules, formula units, etc.

Stoichiometry

Using Dimensional Analysis

<h3>Explanation:</h3>

Step 1: Define

7.8 mol Li

Step 2: Identify Conversions

Avogadro's Number

Step 3: Convert

Set up: $\displaystyle 7.8 \ mol \ Li(\frac{6.022 \cdot 10^{23} \ atoms \ Li}{1 \ mol \ Li})$
Multiply/Divide: $\displaystyle 4.69716 \cdot 10^{24} \ atoms \ Li$

Step 4: Check

We are told to round to 2 sig figs. Follow sig fig rules and round.

4.69716 × 10²⁴ atoms Li ≈ 4.7 × 10²⁴ atoms Li

6 0

2 years ago