A block of aluminum occupies a volume of 15.0 mL and weighs 40.5 g. What is its density?

2. Earth is found in a region of space called the _____ zone?

elena-14-01-66 [18.8K]

Answer:

third zone

Explanation:

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8 0

3 years ago

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List and discuss at least 4 reasons why a laboratory should operate using GLP.

Drupady [299]

Answer:

The list and discussions are stated below:

Explanation:

Good Laboratory Practice (GLP) is extremely important.

1. Organization

With GLP we can guarantee an organized work environment, which is essencial in a laboratory.

2. Safety

GLP promotes laboratory safety for personell, avoiding unecessary risks and preventing accidents.

3. Quality control

GLP ensures that experiments made and products developed in a laboratory have the demanded quality.

4. Reliability of results

GLP promotes quality of results reporting, wich directly influences the reliability of results.

7 0

4 years ago

6 NaOH + 2 Al --> 2 Na3AlO3 + 3 H2 If you start with 258 g of Al, how many moles of Na3AlO3 can you make?

tatyana61 [14]

Solution :

Assuming all Al will be consumed in the reaction.

From the given equation, 2 mole of Al produce 2 mole of $Na_3AlO_3$ .

So, 1 mole of Al produce 1 mole of $Na_3AlO_3$ . .....statement 1)

Number of moles of Al in 258 gram of Al.

$n = \dfrac{mass}{molar\ mass}\\\\n = \dfrac{258}{27}\ moles\\\\n = 9.556 \ moles$

Therefore, from statement 1) number of moles of $Na_3AlO_3$ produced is also 9.556 moles.

7 0

3 years ago

IF A CAPPED GLASS BOTTLE IS THROWN INTO A FIRE, WHAT WILL HAPPEN TO THE BOTTLE AND WHY?

ArbitrLikvidat [17]

Answer:

it will explode (not intensely) there is some oxygen in the bottle so the cap would pop off violently, the longer it stays in the fire the more energy is being pent up.

Explanation:

8 0

3 years ago

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Pulverized coal pellets, which may be approximated as carbon spheres of radius ro= 1 mm, are burned in a pure oxygen atmosphere

Ganezh [65]

Answer:

Explanation:

SO; If we assume that:

P should be the diffusion of oxygen towards the surface ; &

Q should be the diffusion of carbondioxide away from the surface.

Then the total molar flux of oxygen is illustrated by :

$Na,x = - cD_{PQ}\frac{dy_P}{dr} +y_P(NP,x + N_Q,x)$

where;

r is the radial distance from the center of the carbon particle.

Since ;

$N_P,x = - N_Q, x$ ; we have:

$Na,x = - cD_{PQ}\frac{dy_P}{dr}$

The system is not steady state and the molar flux is not independent of r because the area of mass transfer $4\pi r^{2}$ is not a constant term.

Therefore, using quasi steady state assumption, the mass transfer rate $4\pi r^{2}N_{P,x}$ is assumed to be independent of r at any instant of time.

$W_{P}=4\pi r^{2}N_{P,x}$

$W_{P}=-4\pi r^{2}cD_{PQ}\frac{dy_{P}}{dr}$

= constant

The oxygen concentration at the surface of the coal particle $yP,R$ will be calculated from the reaction at the surface.

The mole fraction of oxygen at a location far from pellet is 1.

Thus, separating the variables and integrating result into the following:

$W_{P}\int_{R}^{\infty} \frac{dr}{r^{2}}=-4\pi$

$r^{2}cD_{PQ}\int_{y_{P,R}}^{y_{P,\infty }}dy_{P}$

$-W_{P}\frac{1}{r}\mid ^{\infty }_{R}= -4\pi cD_{PQ}(y_{P,\infty }-y_{P,R})$

$=> W_{P}= - 4\pi cD_{PQ}(1-y_{P,R})R$

The mole of oxygen arrived at the carbon surface is equal to the mole of oxygen consumed by the chemical reaction.

$W_{P} = 4 \pi R^2R"$

$W_{P}= 4\pi R^{2}k_{1}"C_{O_{2}}\mid _{R}$

$W_{P}= 4\pi R^{2}k_{1}"c y _{P,R}$

$-4\pi cD_{PQ}(1-y_{P,R})R= - 4\pi R^{2}k_{1}"c y _{P,R}$

$y_{P,R}=\frac{D_{PQ}}{D_{PQ}+Rk_{1}}$

$y_{P,R}=\frac{1.7 \times 10^{-4}}{1.7\times 10^{-4}+10^{-3}\times 0.1}$

$\mathbf{= 0.631}$

Obtaining the total gas concentration from the ideal gas law; we have the following:

where;

R= $0.082m^3atm/kmolK$

$c=\frac{P}{RT} \\ \\ c=\frac{1}{0.082\times 1450} \\ \\ = 0.008405kmol/m^3$

The steady state $O_2$ molar consumption rate is:

$W_{P}= -4\pi cD_{PQ}(1-y_{P,R})R$

$W_{P}= -4\pi (0.008405)(1.7\times 10^{-4})(1-0.631)(10^{-3})$

$W_{P}= - 6.66\times 10^{-9}kmol/s$

5 0

3 years ago