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3 years ago

Plzzz fastttt answerrr

Chemistry

1 answer:

Colt1911 [192]3 years ago

6 0

Answer:

- Communication between scientists increased.

- Technological advancements were made.

Explanation:

The complete question is

Which answer choices correctly describe why the number of known elements more than doubled by 1861?

Select all that apply.

- Metalworkers began using new metals.

- Communication between scientists increased.

- The American Civil War started.

- Technological advancements were made.

Technological advancement allowed more elements to be properly analysed and classified, and knowledge sharing between scientist by means of communication made it possible for the known number of elements to double by 1861

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Calculating the formula mass of sodium hydroxide

DiKsa [7]

Sodium hydroxide -----> NaOH

7 0

3 years ago

Copper (II) Sulfate pentahydrate, CuSO4 X 5H20 is heated in an open crucible to remove the water. (a) Diagram the lab set up cle

balu736 [363]

The water molecules are not completely removed so additional heating is required.

Explanation:

We have the copper (II) sulfate pentehydrate with the chemical formula CuSO₄ · 5H₂O.

molar mass of CuSO₄ · 5H₂O = 159.6 + 5 × 18 = 249.6 g/mole

Knowing this, we devise the following reasoning:

if in 249.6 g of CuSO₄ · 5H₂O there are 90 g of H₂O

then in 8 g of CuSO₄ · 5H₂O there are Y g of H₂O

Y = (8 × 90) / 249.6 = 2.88 g of water

mass of dried CuSO₄ = mass of CuSO₄ · 5H₂O - mass of H₂O

mass of dried CuSO₄ = 8 - 2.88 = 5.12 g

5.12 g is less that the weighted mass of 6.50 g. We deduce from this that the sample needs additional heating in order to remove all the water (H₂O) molecules.

Learn more about:

hydrates

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6 0

3 years ago

A common fuel additive that is composed of C, H, and O enhanced the performance of gasoline began being phased out in 1999 becau

spayn [35]

Answer:

C₅ H₁₂ O

Explanation:

44 g of CO₂ contains 12 g of C

30.2 g of CO₂ will contain 12 x 30.2 / 44 = 8.236 g of C .

18 g of H₂O contains 2 g of hydrogen

14.8 g of H₂0 will contain 1.644 g of H .

total compound = 12.1 out of which 8.236 g is C and 1.644 g is H , rest will be O

gram of O = 2.22

moles of C, O, H in the given compound = 8.236 / 12 , 2.22 / 16 , 1.644 / 1

= .6863 , .13875 , 1.644

ratio of their moles = 4.946 : 1 : 11.84

rounding off to digits

ratio = 5 : 1 : 12

empirical formula = C₅ H₁₂ O

6 0

3 years ago

What are the mole fraction and the mass percent of a solution made by dissolving 0.21 g KBr in 0.355 L water? (d = 1.00 g/mL.) m

IRISSAK [1]

Answer:

Mol fraction H2O = 0.99991

Mol fraction KBr = 0.00009

mass % KBr = 0.059 %

mass % H2O = 99.941 %

Explanation:

Step 1: Data given

Mass of KBr = 0.21 grams

Molar mass KBr = 119 g/mol

Volume of water = 355 mL

Density of water = 1.00 g/mL

Molar mass water = 18.02 g/mol

Step 2: Calculate mass water

Mass water = 355 mL * 1g /mL

Mass water = 355 grams

Step 3: Calculate moles water

Moles water = mass water / molar mass water

Moles water = 355 grams / 18.02 g/mol

Moles water = 19.7 moles

Step 4: Calculate moles KBr

Moles KBr = 0.21 grams / 119 g/mol

Moles KBr = 0.00176 moles

Step 5: Calculate total moles

Total moles = 19.7 moles + 0.00176 moles

Total moles = 19.70176 moles

Step 6: Calculate mol fraction

Mol fraction H2O = 19.7 moles / 19.70176 moles

Mol fraction H2O = 0.99991

Step 7: Calculate mol fraction KBr

Mol fraction KBr = 0.00176 / 19.70176

Mol fraction KBr = 0.00009

Step 6: Calculate mass %

mass % KBR = (0.21 grams / (0.21 + 355) grams) *100%

mass % KBr = 0.059 %

mass % H2O = (355 grams / 355.21 grams) *100%

mass % H2O = 99.941 %

8 0

3 years ago

When a sample of purified phospholipids is mixed with water, spherical structures called liposomes form.

lutik1710 [3]

Answer:

B). The edges of lipid bilayers sheets fold back on themselves, forming a hollow sphere which releases the ordered waters at the edges.

C) The hydrophobic effect drives aggregation of phospholipids in an aqueous solution.

E) The cross-sectionalarea of the headgroups and acyl chains in the phospholipids are similar

Explanation:

A liposome is simply a tiny bubble also referred to as vesicle that is gotten from the same material as the one a cell membrane is made from. It should be noted that liposomes can be filled with drugs, and then used in the delivery of drugs for diseases such as cancer etc.

Phospholipids afford fluidity, permeability and stability to neural membranes. They're also vital for proper functioning of the receptors, integral membrane proteins, and the ion channels.

The characteristics of phospholipids that enable liposomes to form in water are:

• The edges of lipid bilayers sheets fold back on themselves, forming a hollow sphere which releases the ordered waters at the edges.

• The hydrophobic effect drives aggregation of phospholipids in an aqueous solution.

• The cross-sectionalarea of the headgroups and acyl chains in the phospholipids are similar

3 0

4 years ago