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Kitty [74]
3 years ago
7

Scientists test a hypothesis by?

Chemistry
1 answer:
Novay_Z [31]3 years ago
6 0
They test the hypothesis by experimentation.
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How many moles of gold, Au, are in 3.60 x 10^-5 g of gold?
zlopas [31]
<h3>Answer:</h3>

1.83 × 10⁻⁷ mol Au

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

<u>Math</u>

<u>Pre-Algebra</u>

Order of Operations: BPEMDAS

  1. Brackets
  2. Parenthesis
  3. Exponents
  4. Multiplication
  5. Division
  6. Addition
  7. Subtraction
  • Left to Right

<u>Chemistry</u>

<u>Atomic Structure</u>

  • Reading a Periodic Table
  • Using Dimensional Analysis
<h3>Explanation:</h3>

<u>Step 1: Define</u>

3.60 × 10⁻⁵ g Au (Gold)

<u>Step 2: Identify Conversions</u>

Molar Mass of Au - 196.97 g/mol

<u>Step 3: Convert</u>

  1. Set up:                              \displaystyle 3.60 \cdot 10^{-5} \ g \ Au(\frac{1 \ mol \ Au}{196.97 \ g \ Au})
  2. Multiply:                            \displaystyle 1.82769 \cdot 10^{-7} \ mol \ Au

<u>Step 4: Check</u>

<em>Follow sig fig rules and round. We are given 3 sig figs.</em>

1.82769 × 10⁻⁷ mol Au ≈ 1.83 × 10⁻⁷ mol Au

4 0
3 years ago
Which of the substances are elements please help
ivanzaharov [21]

Answer:

Substances 1 and 2

Explanation:

an element only has 1 kind of atoms :3

6 0
3 years ago
A piece of wood burns to form ash. ____C_____ Water evaporates into steam. ____P_____ A piece of cork is cut in half. ____P_____
IceJOKER [234]

Answer:

A piece of wood burns to form ash - Chemical change

Water evaporates into steam - Physical change

A piece of cork is cut in half. __ Physical change

A bicycle chain rusts. _____Chemical change

Food is digested in the stomach. _____Chemical change

Water is absorbed by a paper towel. _____Physical change

Hydrochloric Acid reacts with zinc. _____Chemical change

A piece of an apple rots on the ground. ____Chemical change

A tire is inflated with air - Physical change

A Plant turns sunlight, CO2, and water into sugar and oxygen. _Chemical change

Sugar dissolves in water - Physical change

Eggs turn into an omelet. _____Chemical change

Milk sours. Chemical change

A popsicle melts. _____Physical change

Turning brownie mix into brownies. Chemical change

Explanation:

Matter undergoes two types of changes: physical changes and chemical changes.

A physical change is one that affects only the physical properties of a substance such as colour, size, shape, etc., and in which no new substances are formed. Physical changes are easily reversible.

Chemical changes are changes which affect the chemical characteristics and properties of a substance such as reactivity, acidity, basicity, etc., resulting in the formation of new substances.

The following changes below are categorized as either physical or chemical changes based on which of the properties of the substance is affected and whether new substances result or not.

A piece of wood burns to form ash - Chemical change

Water evaporates into steam - Physical change

A piece of cork is cut in half. __ Physical change

A bicycle chain rusts. _____Chemical change

Food is digested in the stomach. _____Chemical change

Water is absorbed by a paper towel. _____Physical change

Hydrochloric Acid reacts with zinc. _____Chemical change

A piece of an apple rots on the ground. ____Chemical change

A tire is inflated with air - Physical change

A Plant turns sunlight, CO2, and water into sugar and oxygen. _Chemical change

Sugar dissolves in water - Physical change

Eggs turn into an omelet. _ Chemical change

Milk sours - Chemical change

A popsicle melts. _____Physical change

Turning brownie mix into brownies - Chemical change

3 0
3 years ago
A certain substance X has a normal freezing point of -6.4 C and a molal freezing point depression constant Kf= 3.96 degrees C.kg
Brut [27]

Answer:  1.0\times 10^2g

Explanation:

Depression in freezing point is given by:

\Delta T_f=i\times K_f\times m

\Delta T_f=T_f^0-T_f=(-6.4-(13.6))^0C=7.2^0C = Depression in freezing point

i= vant hoff factor = 1 (for non electrolyte like urea)

K_f = freezing point constant = 3.96^0C/m

m= molality

\Delta T_f=i\times K_f\times \frac{\text{mass of solute}}{\text{molar mass of solute}}\times \text{weight of solvent in kg}}

Weight of solvent (X)= 950 g = 0.95 kg  

Molar mass of non electrolyte (urea) = 60.06 g/mol

Mass of non electrolyte (urea) added = ?

7.2=1\times 3.96\times \frac{xg}{60.06 g/mol\times 0.95kg}

x=1.0\times 10^2g

Thus 1.0\times 10^2g urea was dissolved.

8 0
3 years ago
Write sentences that completely describe each of the chemical reactions shown in these skeleton equations. 11.1
Natasha2012 [34]
Please upload a photo of your question!
6 0
3 years ago
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