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3 years ago

The half-life of Radium-226 is 1590 years. If a sample contains 100 mg, how many mg will remain after 4000 years?

1 answer:

4 0

We can calculate the amount left after 4000 years by using the half-life equation. It is expressed as:

A = Ao e^-kt

where A is the amount left at t years, Ao is the initial concentration, and k is a constant.

From the half-life data, we can calculate for k.

1/2(Ao) = Ao e^-k(1590)
k = 4.36 x 10^-4

A = 100 e^-<span> 4.36 x 10^-4(4000)
</span>A = 17.48 mg

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How much space does 2 x 1022 atoms of copper take up?

pashok25 [27]

Answer:

2044

Explanation:

you just multiply 1022 by 2

6 0

3 years ago

The empirical formula for carbohydrates is CH2O. The molecular weight for a particular carbohydrate is 90.09 grams. What is the

baherus [9]

We find the weight of the empirical formula:
12.0107 + 2 x 1.00794 + 15.9994
= 30.03

Now, we divide the molecular weight by the weight of the empirical formula to find the number of times the empirical formula repeats:
90.09 / 30.03
= 3

The formula is 3(CH₂O)
C₃H₆O₃

6 0

3 years ago

How many moles of glucose does 1.2 x 10^24 molecules represent

sammy [17]

<h3>Answer:</h3>

2.0 mol C₆H₁₂O₆

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

<u>Math</u>

<u>Pre-Algebra</u>

Order of Operations: BPEMDAS

Brackets
Parenthesis
Exponents
Multiplication
Division
Addition
Subtraction

Left to Right

<u>Chemistry</u>

<u>Atomic Structure</u>

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

<u>Stoichiometry</u>

Using Dimensional Analysis

<h3>Explanation:</h3>

<u>Step 1: Define</u>

1.2 × 10²⁴ molecules C₆H₁₂O₆ (glucose)

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

Avogadro's Number

<u>Step 3: Convert</u>

Set up: $\displaystyle 1.2 \cdot 10^{24} \ molecules \ C_6H_{12}O_6(\frac{1 \ mol \ C_6H_{12}O_6}{6.022 \cdot 10^{23} \ molecules \ C_6H_{12}O_6})$
Divide: $\displaystyle 1.99269 \ mol \ C_6H_{12}O_6$

<u>Step 4: Check</u>

<em>Follow sig fig rules and round. We are given 2 sig figs.</em>

1.99269 mol C₆H₁₂O₆ ≈ 2.0 mol C₆H₁₂O₆

3 0

3 years ago

Decide whether a chemical reaction happens in either of the following situations. If a reaction does happen, write the chemical

sineoko [7]

Explanation:

A strip of solid palladium metal is put into a beaker of nicl2

Palladium (Pd) + Nickel Chloride (NiCl2)

To answer this question properly you must refer to the reactivity series.

The activity series is a chart of metals listed in order of declining relative reactivity. The top metals are more reactive than the metals on the bottom.

In this series, Nickel is higher than Palladium. This means that if a Palladium strip is placed into a solution of a Ni salt, then a reaction will not take place, nothing would happen.

Because Pd is lower than Ni in the reactivity series.

There is no reaction so no equation.

7 0

3 years ago

Given 16.2 grams of substance Y, if the substance absorbs 2722 joules of energy and the specific heat of the substance is 9.22 J

snow_tiger [21]

Since the substance absorbs heat, it is expected that the temperature will rise. The formula for the internal energy of a substance is given by the equation:

ΔU = mCpΔT

where:

ΔU = internal energy
m = mass of substance
Cp = specific heat capacity of substance
ΔT = change in temperature

ΔU = 2722 Joules = 16.2 grams (9.22 J/g-°C) (Tf - 26°C)

This gives a final temperature of Tf = 44.22 °C

4 0

3 years ago