Density and Mass Calculations in Science

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Questions and Answers

What is the mass in grams of 85.32 mL of blood plasma with a density of 1.03 g/mL?

85.32 g

87.88 g

87.9 g (correct)

88.65 g

What is the specific gravity of a substance with a density of 1.1 g/cm³?

0.95

1.0

0.9

1.1 (correct)

In the equation for calculating density, what does the term 'density' represent?

Mass times volume

Volume times specific gravity

The volume divided by the mass

The mass divided by the volume (correct)

If a sample of rubbing alcohol has a specific gravity of 0.789, what is its density in g/mL?

0.789 g/mL Signup and view all the answers

Which conversion factor should be used to convert 5.0 g of a substance with a density of 1.05 g/mL to mL?

1 mL/1.05 g Signup and view all the answers

How is the displaced volume of an object determined when calculating density?

By subtracting the initial water level from the final water level. Signup and view all the answers

What is the formula for calculating density?

Density = Mass / Volume Signup and view all the answers

Which statement about conversion factors is correct?

They must be written as fractions to be useful. Signup and view all the answers

If a conversion factor is expressed as 2.21 lb = 1 kg, which of the following is correct?

2.21 lb can be used to convert kilograms to pounds. Signup and view all the answers

What is the result of using the factor-label method correctly?

Only the final unit remains after cancellation of unwanted units. Signup and view all the answers

What is the correct method to convert 130 lb into kilograms using a conversion factor?

130 lb x 1 kg/2.21 lb Signup and view all the answers

Which of the following statements about density is true?

Density can change based on environmental factors. Signup and view all the answers

What is the scientific notation for the standard number 0.000138?

1.38 x 10-4 Signup and view all the answers

Which of the following statements is true about numbers with negative exponents in scientific notation?

They are decimal numbers less than one. Signup and view all the answers

How would you express the number 2500 in scientific notation?

2.5 x 103 Signup and view all the answers

What is the result when converting 2.80 x 10–2 back to a standard number?

0.0280 Signup and view all the answers

Which of the following represents 1.28 x 107 in standard form?

128,000,000 Signup and view all the answers

What is 520000 expressed in scientific notation with three significant figures?

5.20 x 10^5 Signup and view all the answers

Which of the following is the correct representation of 0.12 in scientific notation?

1.2 x 10-2 Signup and view all the answers

What is a characteristic of gas?

Expands to fill its container Signup and view all the answers

Which of the following is an example of a chemical change?

Rusting of iron Signup and view all the answers

What is a pure substance?

Has a constant composition regardless of sample size Signup and view all the answers

Which of the following properties can be observed without changing the substance?

Melting point Signup and view all the answers

What defines a homogenous mixture?

Composition is uniform throughout Signup and view all the answers

Which statement is true about a compound?

Formed by chemically joining two or more elements Signup and view all the answers

Which of the following describes a physical change?

The crystallization of salt from water Signup and view all the answers

How can a mixture be separated?

By physical means Signup and view all the answers

What is the primary focus of chemistry?

The study of matter and its properties Signup and view all the answers

Which of the following is a naturally occurring form of matter?

Silk Signup and view all the answers

Which substances listed below are considered chemicals?

Fruit, milk, and breakfast cereal Signup and view all the answers

What is the first step in the scientific method?

Make observations and ask questions Signup and view all the answers

Which of the following correctly distinguishes between natural and synthetic matter?

Natural matter includes substances like gemstones; synthetic matter includes substances like Styrofoam. Signup and view all the answers

Which of these is an example of a synthetic matter?

Styrofoam Signup and view all the answers

What best describes the composition of chemicals?

Chemicals consist of identical compositions and properties throughout Signup and view all the answers

What is the purpose of conducting experiments in the scientific method?

To gather data to support or refute the hypothesis Signup and view all the answers

What is the primary purpose of conducting experiments in the scientific method?

To gather evidence that supports or contradicts the hypothesis Signup and view all the answers

Which of the following describes a liquid state of matter?

It has a definite volume but takes the shape of its container Signup and view all the answers

What happens to a hypothesis if experimental results do not support it?

It can be revised or modified Signup and view all the answers

How do solid particles behave in a solid state of matter?

They lie close together in a regular pattern Signup and view all the answers

What is a hypothesis in the context of the scientific method?

An educated guess that can be tested Signup and view all the answers

Which statement correctly identifies an observation?

I notice my heart rate increases when I run. Signup and view all the answers

Which of the following statements about gases is true?

They occupy both volume and shape of their container Signup and view all the answers

Which of the following represents a conclusion drawn from an experiment?

My weight loss is due to exercising more. Signup and view all the answers

Study Notes

Matter and Measurement

Chemistry is the study of matter, its properties, and transformations.
Matter is anything that has mass and takes up space (volume).
Naturally occurring matter includes cotton, silk, hair, sand, gemstones, and digoxin (a cardiac drug).
Synthetic (human-made) matter includes nylon, polyester, styrofoam, ibuprofen, and many antibiotics.
Matter is another word for all substances that make up the world (e.g., antacid tablets, water, glass, air).
Chemistry studies the composition, structure, and properties of matter, and the changes it undergoes.
All matter is made up of basic building blocks called atoms.
Chemicals are substances with consistent composition and properties.
Chemicals are often created by chemists and are used in everyday products (e.g., toothpaste).
Examples of chemicals in toothpaste include calcium carbonate (abrasive), sorbitol (prevents hardening), titanium dioxide (whitener), triclosan (antibacterial), and sodium fluorophosphate (strengthens enamel).
Other examples of kitchen chemicals include silicon dioxide or glass, chemically treated water, Metal alloys, Natural polymers, and natural gas.
Sunlight is energy, not matter and thus does not contain chemicals.
Fruit, milk, and breakfast cereal are matter and contain chemicals.

The Scientific Method

The scientific method is a set of general principles used in scientific thinking.
Scientists first make observations and ask questions about natural phenomena.
Next, they propose a hypothesis, a possible explanation for the observations.
Experiments are then conducted to test the hypothesis.
Results are analyzed, leading to a conclusion regarding the validity of the hypothesis.
If the experimental results do not support the hypothesis, it can be modified.

Discovery of Penicillin

Penicillin was discovered through observation and the scientific method.

Using the Scientific Method

The scientific method is used in everyday situations, such as determining if you are allergic to cats.
Observations lead to a hypothesis, which can be tested through additional experiments and observations.

Classification of Matter

Matter can be classified into pure substances (elements and compounds) and mixtures.
Pure substances have a constant composition regardless of sample size or origin, and cannot be broken down into other pure substances by physical changes.
- Examples include diamonds, sugar (C12H22O11) and water (H2O).
Compounds are chemically joined elements.
- Example, table salt (NaCl) is a compound composed of sodium and chlorine.
Elements cannot be broken down into simpler substances through chemical change.
- Example, aluminum (Al).
Mixtures contain more than one substance.
- Mixtures can be homogeneous (uniform composition, like brass (copper and zinc)) or heterogeneous (uneven composition, like water and copper).

Measurements

Measurements consist of a number and a unit.
Numbers without units are meaningless.
The metric system uses units like meters, liters, and grams.
The English system uses units like feet, gallons, and pounds.
Exact numbers result from counting or definitions.
Inexact numbers (measured values) have some uncertainty.

Significant Figures

Significant figures represent meaningful digits in a measurement.
All nonzero digits are significant.
Zeros are significant when they are between nonzero digits, at the end of a number with a decimal, and in scientific notation.
Zeros at the beginning of a number are not significant.

Density

Density is the ratio of mass to volume.
Density = mass/volume (g/mL)
Density is an intensive property.
Water density is roughly 1.0 g/mL.
Less dense substances float on denser substances.

Converting Units

The factor-label method (dimensional analysis) is used to convert units.
Conversion factors are written as ratios to cancel out unwanted units.

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Description

This quiz covers fundamental concepts in density and specific gravity calculations. Specifically, it will test your ability to convert volume to mass and understand the relationship between density and gravity. Designed for students studying basic chemistry or scientific principles.