4. define a tsunami

Answer: iron atoms

Explanation:

According to avogadro's law, 1 mole of every substance weighs equal to the molecular mass and contains avogadro's number of particles.

contains= 2 atoms of iron

contains=  atoms of iron

thus 0.32 moles of contains=  atoms  of iron

Thus the sample would have iron atoms.

The mass of hydrogen gas obtained is 0.068 g of hydrogen gas.

The equation of the reaction is;

Ca(s) +2H2O(l) →Ca(OH)2(aq) + H2(g)

We have to obtain the number of moles of hydrogen gas produced using the information in the question.

P =  988mmHg - 17.54 mmHg = 1.28 atm

V = 641 mL or 0.641 L

T = 20 + 273 = 293 K

n = ?

R = 0.082 atmLK-1mol-1

From;

PV = nRT

n = PV/RT

n = 1.28 atm × 0.641 L/ 0.082 atmLK-1mol-1 × 293 K

n = 0.82/24.026

n = 0.034 moles

Mass of hydrogen =  0.034 moles × 2 g/mol = 0.068 g of hydrogen gas

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Answer:

There is 0.0677 grams of H2 gas obtained

Explanation:

Step 1: Data given

The total pressure (988 mmHg) is the sum of the pressure of the collected hydrogen + the vapor pressure of water (17.54 mmHg).  

ptotal = p(H2)+ p(H2O)

p(H2) = ptotal - pH2O = 988 mmHg - 17.54 mmHg = 970.46 mmHg

Step 2: Calculate moles of H2 gas

Use the ideal gas law to calculate the moles of H2 gas

PV = nRT

n = PV / RT

 ⇒ with p = pressure of H2 in atm = 970.46 mmHg * (1 atm /760 mmHg) = 1.277 atm

⇒ V = volume of H2 in L = 641 mL x (1 L / 1000 mL) = 0.641 L

⇒ n = the number of moles of H2 = TO BE DETERMINED

⇒ R = the gas constant = 0.08206 L*atm/K*mol

⇒ T = the temperature = 20.0 °C = 293.15 Kelvin

n = (1.277)(0.641) / (0.08206)(298.15) = 0.0335 moles H2

Step 3: Calculate mass of H2

Mass of H2 = moles H2 ¨molar H2

0.0335 moles H2 * 2.02 g/mol H2  = 0.0677g H2

There is 0.0677 grams of H2 gas obtained

Answer:

Three atoms are attached to the central atom in NF3.

Explanation:

The central atom is always regarded as the atom having the least electronegativity in a molecule or ion. We can decide on what atom should be the central atom by comparing the relative electro negativities of the atoms in the molecule or ion.

If we consider NF3, we can easily see that nitrogen is less electronegative than fluorine, hence nitrogen is the central atom in the molecule. We can also observe from the molecular model that three atoms of fluorine were attached to the central atom. Hence there are three atoms attached to the central atom in the molecule NF3.

Answer:

1. micro

2. centi

3. milli

4. kilo

Explanation:

Prefixes, in mathematical exponents, are defined as the alphabetical names associated with the mathematical factors. Some examples are as follows:

10⁶ = Mega

10⁹ = Giga

10⁻⁹ = Nano

10⁻¹² = Pico

So, in order to name the metric system prefixes associated with each of the given mathematical factor, we first convert the factor into exponent form and then write its prefix, as follows:

10⁻⁶ = micro

1/100 = 0.01 = 1 x 10⁻² = centi

0.001 = 1 x 10⁻³ = milli

1000 = 1 x 10³ = kilo